The group of Martin R. Larsen is focusing on the application of biological mass spectrometry in proteomics, especially the characterization of post-translational modifications in proteins and their influence on biological systems. The group is working with a large variety of biological systems and human diseases through collaborations with both academics on Universities and hospitals, and industry.
The primary focus in the group is to develop new and efficient quantitative mass spectrometric and affinity chromatographic strategies for the characterization of phosphorylated and glycosylated proteins from highly complex mixtures and apply these strategies to the study of various biological systems. The current larger projects in the group are:
- Development of large scale quantitative strategies for the identification and characterization of phosphorylated and sialylated proteins from low amount of cell material (e.g., primary cells).
- Characterization of the phosphorylation-dependent calcium signaling in nerve terminals after various stimuli, i.e., depolarization.
- Characterization of phosphorylation dependent signaling events in pancreatic beta-cells exposed to various pro-inflammatory cytokines such as Interleukine-1β.
- Characterization of altered glycosylation (i.e., sialylation) on surface proteins of cancer cells and their influence on metastasis.
- Characterization of microparticles and exosomes from apoptotic cells and body-fluids
- Membrane proteomics and the characterization of phosphorylated and sialylated proteins in membranes.
- Kinomics - the study of kinases and their presence and activity in the cell using kinase inhibitor affinity purification and mass spectrometry. Characterization of kinases in nerve-terminals.
- Biomarker discovery with the focus on glycosylated proteins in various body-fluids such as plasma, serum and cerebrospinal fluid (type 2 diabetes, Alzheimers Disease and other CNS diseases)
Beside the above mentioned projects we have a large number of small projects mainly through external collaborations.
For more information on the different areas and projects please see extended CV of Martin R. Larsen
Reseach assistant Inga Boll
Visiting scientist Arkadiusz Nawrocki
Martin Røssel Larsen is also head of Centre for Clinical Proteomics.
1: Methodological development for modification specific proteomics on biological systems.
My research team is at the cutting edge of method development for characterizing PTMs such as phosphorylation and glycosylation in immortalized cells in culture. Having developed several methods for assessing modified peptides from complex mixtures lately we are very confident that we only observe the tip of the iceberg and do not detect the transient or low abundant biologically important modifications. In addition, recent results obtained in my group suggest that the current methods for PTMs characterization are not applicable for true in vivo studies using primary cells originating directly from animals or humans. For example investigating the phosphoproteome of a cell after external stimulation are mostly performed only using cell cultures that have been serum-starved to reduce the basal phosphorylation caused by growth factors in the medium. Serum-starvation is frequently not applicable to primary cells and tissues which undergo apoptosis under such culture conditions. Other factors also influence the analysis of primary cells and tissues, including the presence of extracellular matrix, mixed cell populations and the significantly reduced available sample for microanalysis. We speculate that not only phosphorylation but all kind of PTMs will be much more challenging to characterize from true in vivo biological systems and that current methods for analyzing PTMs are not appropriate for true in vivo studies. We have therefore initiated a focused research program aiming at developing new and more sensitive mass spectrometric methods for the assessment of PTMs from primary cells, tissues and body-fluids, biological material that cannot be manipulated prior to analysis. We will combine the newly developed affinity enrichment methods with extensive multidimensional separation methods in order to achieve the most sensitive comprehensive technique for phosphoproteimics and glycomics.
Another problem in current PTM analysis is the quantitative assessment of different PTMs in proteins. After identifying for example phosphorylation sites, the next obvious step is to quantify the changes in phosphorylation in different situations. We will continue optimizing methods for more complex samples and develop new methods for accurate quantification of PTMs from very small amount of material using stabile isotope labelling in combination with nano-purification techniques and accurate mass spectrometry.
2: Characterization of the molecular mechanism of Synaptic Vesicle Endocytosis.
There are many billions of neurons in the human brain, each with the ability to influence many other cells. An average neuron will make approximately 10,000 contacts, or synapses, with other neurons while receiving a similar input itself. Therefore, sophisticated mechanisms are essential to enable efficient communication within this highly complex system. These mechanisms are functionally localized at synapses which are the contact points between neurons. The presynaptic side of the synapse (the presynaptic nerve terminal) is the focus of this study. Although many kinds of synapses exist within the brain, they can be divided into two distinct populations: electrical synapses and chemical synapses. In the brain, the number of electrical synapses is significantly lower than the number of chemical synapses. Electrical synapses permit direct, passive flow of electrical current from one neuron to another and therefore allow much faster communication than chemical synapses. In contrast, chemical synapses use small signalling molecules, or neurotransmitters (e.g. acetylcholine, dopamine or glutamate), to enable cell-to-cell communication. Neurotransmitters are stored in small organelles termed synaptic vesicles (SVs), which are normally at rest bound to the cytoplasmic cytoskeleton. Upon depolarization, neurotransmitters are released by the presynaptic terminal into the space between the pre- and postsynaptic cells, the synaptic cleft, and bind and activate specific receptors at the post-synaptic membrane to initiate signalling events. After release of neurotransmitters the SV is retrieved back into the nerve terminal. This overall process is called synaptic transmission.
In the chemical synapse, the release of neurotransmitters is triggered by the influx of calcium through ion-channels in the presynaptic membrane. An increase of Ca2+ in the presynaptic nerve terminal leads to a multitude of molecular events resulting in release of neurotransmitters to the synaptic cleft. SVs are firstly released from the cytoskeleton and transported to the plasma membrane at the synapse where they fuse with the presynaptic plasma membrane to release their content into the synaptic cleft – this is called exocytosis. After release of the neurotransmitter molecules, the used SVs are retrieved, also via a Ca2+-regulated process, back into the pre-synaptic cell for another round of neurotransmitter filling and exocytosis – this is called endocytosis. Both exo- and endocytosis are controlled by phosphorylation and dephosphorylation of synaptic proteins by various kinases and phosphatases that become activated as a result of Ca2+ influx.
Previously we have in close collaboration with Prof Phillip J. Robinson, Children’s Medical Research Institute (CMRI), Sydney, Australia found more than 50 phosphorylation sites on 4 different proteins that participate in the SV endocytosis. In future projects we will (1) complete a full map of phosphorylated proteins in the synaptosomes and quantify their changes during depolarization, (2) elucidate the biological role of these phosphorylation sites in protein interaction and complex assembly, (3) quantify the changes of phosphorylation of synaptosomal proteins in neurological diseases e.g., epilepsy.
3: Unrevealing the pathogenesis of Type 1 Diabetes Mellitus.
Accumulating evidence supports a role for cytokines, especially interleukin 1b (IL-1b), released during this inflammation, in the pathogenesis of T1DM. IL-1b, either alone, or in combination with other cytokines (tumour necrosis factor-a and interferon g) induces the production of toxic nitric oxide (NO) free radicals by the beta-cell itself, which leads to beta-cell self-destruction. We have initiated a research project elucidating the phosphorylation events involved in interleukin 1b signal transduction. We have discovered from low amount of material a large number of phosphorylated peptides and new phosphorylation sites that have not been characterized and quantified before. This study will be extended to elucidate the phosphorylation events in the signal transduction pathways of the three pro-inflammatory cytokines; IL-1b, TNFa and INFg and the crosstalk between those pathways.
Knowledge on the exact molecular mechanisms used by each cytokine in signalling cascades is still very limited. The phosphorylation events of the proteins in the downstream signalling pathways (STAT1, IKK-NFκB and MAPK) are extensively characterized primarily because they are shared by many other signalling pathways (e.g., EGF and PDGF). However, information on the regulatory phosphorylation events of the proximal membrane complexes are relatively limited. Knowledge of the precise regulation of these complexes by phosphorylation is essential to the future development of new pharmaceuticals designed to stop the development of T1DM by blocking the phosphorylation dependent activation (e.g., by inhibiting an involved kinase). Drugs inhibiting proteins later in the pathway will consequently effect many other functions in the cell and thus cause many unwanted side effects.
4: Investigation of the influence of altered protein glycosylation on cancer development and metastasis.
Protein glycosylation is among the most common PTMs known in nature. Glycosylation is difficult to analyze by any biochemical methods due to the chemically very similar monosaccharide building blocks and pronounced glycosylation site heterogeneity and micro-heterogeneity of the carbohydrate chains with respect to branching patterns and monosaccharide composition. The biological role of protein glycosylation varies from conformational stability, protection against degradation, to molecular and cellular recognition in for example development, growth and cellular communication.
It is well known that glycosylation patterns in chronic disease can be highly aberrant as a consequence of changes in the expression or activity of glycosyltransferases or other factors affecting the glycan biosynthesis. Many extracellular and surface glycoproteins contain sialic acid (SA) as the monosaccharide located on the reducing end of the glycans. These can either be located on the glycoproteins as monomer, dimers, trimers or as large polysialic acid structures comprising of more than 200 SA residues. It has previously been demonstrated that cancer development and staging may be associated with a significant over-representation of SA on the cell surface glycoproteins of cancer cells compared to normal cells (e.g., [Dall'Olio, F., Chiricolo, M. Sialyltransferases in cancer. Glycoconj J. 2001, 18(11-12), 841-50]). The transformation of a tumor from benign to malignant is associated with increased SA content on the surface glycoproteins. Also it is well known that the amount of free SA and lipid and protein bound SA is elevated in plasma from cancer patients compared to healthy individuals.
Based on the methods developed in my group for selective isolation of sialylated peptides we have initiated a research program together with Professor Dr. Med. Henrik Ditzel, Medical Biotechnology Center, Odense University Hospital, Denmark and Dr. Med. Niels H.H. Heegaard, State Serum Institute, Denmark to investigate the role of glycosylation, especially sialylation, in cancer development. This is primarily a basic research project aiming at understanding the function of sialic acids and glycosylation in relation to cancer. In this project we will correlate the expression and activity of sialyltransferases in cancer cells and “normal” cells with the sialylation degree of the surface glycoproteins using stabile isotope labelling, TiO2 chromatography, hydrophilic interaction chromatography and mass spectrometry.
5: Biomarker discovery program
The aim of these clinical proteomics project is to investigate the possibility of detecting modified biomarkers (e.g., phosphorylated, glycosylated, oxidized etc.) indicative of a recent onset of T1DM and cancers in plasma. We have taken two different approaches for this research.
The primary focus of this research is to investigate if glycosylated proteins, especially sialylated glycoproteins can be used as biomarkers for a number of diseases including Type 2 diabetes, cancers, Alzheimers Disease and other CNS related diseases.
Manuscripts under revision or in preparation
75. Jensen SS, Le Bihan MC, Lainé J, McGuire J, Pociot F, Larsen MR. Characterization of Membrane-shed Microvesicles from Cytokine-Stimulated Beta-Cells using Proteomics Strategies. in preparation.
74. Jensen SS, Bahl JMC, Heegaard NHH, Larsen MR. Characterization of the Human Cerebrospinal Fluid N-linked sialioproteome by Titanium Dioxide Affinity Chromatography and Mass Spectrometry. in preparation.
73. Solis N., Larsen M.R. and Cordwell S.J. Improved accuracy of cell surface shaving proteomics in Staphylococcus aureus using a false positive control. Submitted to Proteomics.
72. Bache, N., Graham, M.E., McCluskey, A., Robinson, P.J., Larsen, M.R. N-terminally SPITC labelling of phosphorylated peptides and sialylated glycopeptides directly on Titanium dioxide micro-columns combined with MALDI tandem Mass Spectrometry. Submitted to Analytical Chemistry.
71. Chircop, M., Sarcevic, B., Larsen M.R., Malladi, C.S., Graham, M.E., Zavortink M., Chau, N., Smith, C.M., Quan, A., Anggono, V., Graham, M.E. and Robinson P.J. Mitotic phosphorylation of dynamin II at serine-764. In preparation.
Articles published or accepted
69. Thingholm, T.E., Jensen, O.N. and Larsen M.R. Analytical strategies for phosphoproteomics. Proteomics. 2009, 9(6), 1451-68.
68. Thingholm, T.E. and Larsen, M.R. Enrichment and separation of mono- and multi-phosphorylated peptides using Sequential elution from IMAC prior to mass spectrometric analysis. Methods Mol Biol. 2009, 527, 57-66.
67. Thingholm, T.E., Jensen, O.N. and Larsen, M.R. The use of titanium dioxide micro-columns to selectively isolate phosphopeptides from proteolytic digests. Methods Mol Biol. 2009, 527, 67-78.
66. Krintel, C., Osmark, P., Larsen, M.R., Resjö, S., Logan, D. and Holm, C. Ser649 and Ser650 are the major determinants of protein kinase A-mediated activation of human hormone-sensitive lipase against lipid substrates. PLoS One. 2008, 3(11), e3756.
65. Olsen, B.B., Larsen, M.R., Boldyreff, B., Niefind, K. and Issinger O-G. Exploring the intramolecular phosphorylation sites in human Chk2. Mutat Res. 2008, 646(1-2):50-9.
64. Bahl, J., Jensen, S.S., Larsen M.R., Heegaard, N.H.H. Characterization of the human cerebrospinal fluid phosphoproteome by titanium dioxide affinity chromatography and mass spectrometry. Anal Chem. 2008, 80(16):6308-16.
63. Thingholm, T.E., Larsen, M.R., Ingrell, C.R., Kassem, M., Jensen O.N. TiO(2)-based phosphoproteomic analysis of the plasma membrane and the effects of phosphatase inhibitor treatment. J Proteome Res. 2008, (8), 3304-13.
62. Chrétien A, Dierick JF, Delaive E, Larsen MR, Dieu M, Raes M, Deroanne CF, Roepstorff P, Toussaint O. Role of TGF-beta1-independent changes in protein neosynthesis, p38alphaMAPK, and cdc42 in hydrogen peroxide-induced senescence-like morphogenesis. Free Radic Biol Med. 2008, 44(9), 1732-51.
61. Craft, G.E., Graham, M.E., Bache, N., Larsen, M.R., Robinson, P.J. The in vivo phosphorylation sites in multiple isoforms of amphiphysin I from rat brain nerve terminals. Mol Cell Proteomics. 2008, 7(6), 1146-61.
60. Larsen, A.K., Lametsch, R., Elce, J.S., Larsen, J.K., Thomsen, B., Larsen, M.R., Lawson, M.A., Greer, P.A., Ertbjerg, P. Genetic disruption of calpain correlates with loss of membrane blebbing and differential expression of RhoGDI-1, cofilin and tropomyosin. Biochem J. 2008, 411(3), 657-66.
59. Thingholm, T.E., Jensen O.N., Robinson P.J. Larsen, M.R. SIMAC - A phosphoproteomic strategy for the rapid separation of mono-phosphorylated from multiply phosphorylated peptides. Mol Cell Proteomics. 2008, 7(4), 661-71.
58. Jensen, S.S. and Larsen, M.R. Evaluation of phosphopeptide enrichment procedures. Rapid Commun Mass Spectrom. 2007, 21(22), 3635-3645.
57. Larsen, M.R., Jensen, S.S., Jakobsen, L.A., Heegaard, N.H. Exploring the Sialiome using Titanium Dioxide chromatography and Mass Spectrometry. Mol Cell Proteomics. 2007, 6(10), 1778-1787.
56. Banuelos S, Omaetxebarria MJ, Ramos I, Larsen MR, Arregi I, Jensen ON, Arizmendi JM, Prado A, Muga A. Phosphorylation of both nucleoplasmin domains is required for activation of its chromatin decondensation activity. J. Biol Chem. 2007, 282(29), 21213-21.
55. Palmisano G, Sardanelli AM, Signorile A, Papa S, Larsen MR. The phosphorylation pattern of bovine heart complex I subunits. Proteomics. 2007, 7(10), 1575-83.
54. Jovceva E, Larsen MR, Waterfield MD, Baum B, Timms JF. Cofilin phosphorylation: a homeostatic sensor of lamellipodial actin levels during protrusion dynamics. J Cell Sci. 2007, 120, 1888-97.
53. Graham ME, Anggono V, Bache N, Larsen MR, Craft GE, Robinson PJ. The in vivo phosphorylation sites of rat brain dynamin I. J Biol. Chem. 2007, 18, 282(20), 14695-14707.
52. Thingholm TE., Jorgensen TJD., Jensen ON and Larsen MR. Highly selective enrichment of phosphorylated peptides using titanium dioxide. Nature Protocols, 2006, 4, 1929-1935.
51. Labbate M, Zhu H, Thung L, Bandara R, Larsen MR, Willcox MD, Givskov M, Rice SA, Kjelleberg S. Quorum sensing regulation of adhesion in Serratia marcescens MG1 is surface dependent. J Bacteriol. 2007, 189(7):2702-11.
50. Verrills NM, Pou'ha S, Liu M, Liaw TYE, Larsen MR, Ivery M, Marshall G, Gunning P, Kavallaris M. (2006) Alterations in gamma-actin mediate resistance to tubulin-targeted drugs in childhood leukemia. J Natl Cancer Inst. 2006, 98(19), 1363-74.
49. Larsen M.R., Trelle M.B., Thingholm T.E. and Jensen O.N. Analysis of posttranslational modifications of proteins by tandem mass spectrometry. Biotechniques. 2006, 40(6), 790-8.
48. Ferreira S, Hjerno K, Larsen MR, Wingsle G, Larsen P, Fey S, Roepstorff P, Pais MS. Proteome Profiling of Populus euphratica Oliv. Upon Heat Stress. Ann Bot (Lond). 2006, 98(2):361-77.
47. Stelzer, S., Egan, S., Larsen, M.R., Bartlett, D.H., and Kjelleberg, S. Unravelling the role of the ToxR-like transcriptional regulator WmpR in the marine antifouling bacterium Pseudoalteromonas tunicata. Microbiology. 2006, 152, 1385-94.
46. Karlsen AE, Larsen ZM, Sparre T, Larsen MR, Mahmood A, Størling J, Roepstorff P, Wrzesinski K, Larsen PM, Fey S, Nielsen K, Heding P, Ricordi C, Johannesen J, Kristiansen OP, Christensen UB, Kockum I, Luthman H, Nerup J, and Pociot F. Immune-mediated beta-cell destruction in vitro and in vivo - a pivotal role for galectin-3. Biochem Biophys Res Commun. 2006, 26, 344(1), 406-15.
45. Rinalducci, S., Larsen, M.R., Mohammed, S, Zolla L. Novel protein phosphorylation site identification in spinach stroma membranes by titanium dioxide microcolumns and tandem mass spectrometry. J Proteome Res. 2006, 5(4):973-82.
44. Lametsch, R., Kristensen, L., Larsen, M.R., Therkildsen, M., Oksbjerg, N., and Ertbjerg, P. Changes in the muscle proteome following compensatory growth in pigs. J Anim Sci. 2006, 84(4), 918-24.
43. López-Villar E., Monteoliva L., Larsen M.R., Sachon E., Mohammed S., Pardo M., Pla J., Gil C., Roepstorff P. and Nombela C. Genetic and proteomic evidence supports cell surface localization for yeast enolase. Proteomics. 2006, Suppl 1:S107-18.
42. Larsen, M.R., Thingholm, T.E., Jensen, O.N., Roepstorff, P and Jorgensen T.J.D. Highly selective enrichment of phosphorylated peptides from peptide mixtures using titanium dioxide microcolumns. Mol Cell Proteomics 2005, 4(7), 873-86.
41. Sparre T, Larsen MR, Heding PE, Karlsen AE, Jensen ON, Pociot F. Unravelling the Pathogenesis of Type 1 Diabetes with Proteomics – present and future directions. Mol Cell Proteomics 2005, 4(7), 873-86.
40. Larsen, M.R., Højrup P and Roepstorff P. Characterization of gel-separated glycoproteins using two-step proteolytic digestion combined with sequential micro-columns and mass spectrometry. Mol Cell Proteomics. 2005, 4(2), 107-19.
39. Kristensen, L., Larsen, M.R., Højrup, P., Issinger, O-G. and Guerra, B. Phosphorylation of the regulatory b-subunit of protein kinase CK2 by checkpoint kinase Chk1: identification of the in vitro CK2-b phosphorylation site. FEBS Lett. 2004, 569(1-3):217-23.
38. Fleckenstein B., Qiao S-W., Larsen MR., Jung G., Roepstorff P., and Sollid LM. Molecular basis of covalent complexes between tissue transglutaminase and gliadin peptides. J Biol Chem. 2004, 279(17), 17607-16.
37. Hjerrild M, Stensballe A, Rasmussen TE, Kofoed CB, Blom N, Sicheritz-Ponten T, Brunak S, Larsen MR, Jensen ON and Gammeltoft S. Identification of phosphorylation sites in protein kinase A substrates using artificial neural networks and mass spectrometry. J Proteome Res. 2004, 3(3), 426-33.
36. Larsen MR, Graham M, Robinson PJ and Roepstorff P. Improved mass spectrometric detection of hydrophilic phosphopeptides using graphite powder micro-columns. Mol Cell Proteomics 2004, 3, 456-465.
35. K. Nielsen, T. Sparre, M.R. Larsen, S.J. Fey, P. Mose Larsen, P. Roepstorff, J. Nerup and A.E. Karlsen. Protein expression changes during [[beta]]-cell maturation are associated with IL-1[[beta]] sensitivity. Diabetologia, 2004, 47(1), 62-74.
34. Sparre T, Reusens B, Cherif H, Larsen MR, Roepstorff R, Fey SJ, Mose Larsen P, Remacle C and Nerup J. Proteome analysis of islets of Langerhans exposed to intrauterine low protein diet. Diabetologia, 2003, 46(11), 1497-511.
33. Tan TC, Valova VA, Malladi CS, Graham ME, Berven LA, Jupp OJ, Hansra G, McClure SJ, Sarcevic B, Boadle RA, Larsen MR, Cousin MA, Robinson PJ. Cdk5 is essential for synaptic vesicle endocytosis. Nat Cell Biol. 2003, 5(8), 701-10.
32. Larsen MR, Cordwell SJ, Roepstorff P. Graphite powder as an alternative to reversed phase material for desalting and concentration of peptide mixtures prior to mass spectrometric analysis. Proteomics 2002, 2, 1277–1287.
31. Cordwell SJ, Larsen MR, Cole RT, Walsh BJ. Comparative proteomics of Staphylococcus aureus and the response of methicillin resistant and sensitive strains to Triton X-100. Microbiology 2002, 148(Pt 9), 2765-81.
30. Shaw AC, Larsen MR, Roepstorff P, Christiansen G and Birkelund S. Identification and charcterization of a novel Chlamydia trachomatis reticulate body protein. FEMS Microbiol Lett. 2002, 212(2), 193-202.
29. Shaw AC, Vandahl BB, Larsen MR, Roepstorff P, Gevaert K, Vandekerckhove J, Christiansen G and Birkelund S. Characterization of a secreted Chlamydia Protease. Cell Microbiol. 2002, 4(7), 411-24.
28. Skylas DJ, Cordwell SJ, Hains PG, Larsen MR, Basseal DJ, Walsh BJ, Blumenthal C, Rathmell W, Copeland L and Wrigley CW. Heat shock of wheat during grain filling: characterisation of proteins associated with heat-tolerance using a proteome approach. Journal of Cereal Science 2002, 35, 175-188.
27. Janssen MJFW, Van Voorst F, Ploeger GEJ, Larsen PM, Larsen MR, Kroon AIPM, and Kruijff B. Identification of the interaction between phosphatidylcholin and the mitochondrial glycerol-3-phosphate dehydrogenase from yeast (Gut2p) by photolabeling. Biochemistry 2002 41(18), 5702-5711.
26. Pedersen SK, Christiansen J, Hansen TO, Larsen MR, Nielsen FC. Human insulin-like growth factor II leader 2 mediates internal initiation of translation. Biochem J 2002, 363(Pt 1), 37-44.
25. Shaw AC, Gevaert K, Demol H, Hoorelbeke B, Vandekerckhove J, Larsen MR, Roepstorff P, Holm A, Christiansen G, Birkelund S. Comparative proteome analysis of Chlamydia trachomatis A, D and L2. Proteomics, 2002, 2, 164-186.
24. Larsen MR, Sorensen GL, Fey SJ, Larsen PM, Roepstorff P. Phospho-proteomics: Evaluation of the use of enzymatic de-phosphorylation and differential mass spectrometric peptide mass mapping for site specific phosphorylation assignment in proteins separated by gel electrophoresis. Proteomics 2001, 2, 223-238.
23. Sparre T, Nielsen K, Mose Larsen P, Fey SJ, Larsen MR, Andersen HU, Roepstorff P, Pociot F, Karlsen AE, Nerup J. Proteome analysis used in the discovery of molecular mechanisms involved in the pathogenesis of Type 1 Diabetes Mellitus. Proceedings of the Swiss Proteomics Society 2001, Functional Proteomics, ISBN 2-88476-002-4, 2001, 47-52
22. Larsen MR, Larsen PM, Fey SJ, Roepstorff P. Characterization of stress induced processing of enolase 2 from Saccharomyces cerevisiae by 2-D gel electrophoresis and Mass spectrometry. Electrophoresis 2001, 22, 566-575.
21. Larsen PM, Fey SJ, Larsen MR, Nawrocki A, Andersen HU, Kahler H, Heilmann C, Voss MC, Roepstorff P, Pociot F, Karlsen AE, Nerup J. Proteome analysis of IL-1b induced changes in protein expression in rat islets of Langerhans. Diabetes 2001, 50(5), 1056-63.
20. Jensen HH, Hjerrild M, Guerra B, Larsen MR, Hojrup P, Boldyreff B. Phosphorylation of the Fas associated factor FAF1 by protein kinase CK2 and identification of serines 289 and 291 as the in vitro phosphorylation sites. Int J Biochem Cell Biol 2001, 33(6), 577-89.
19. Brymora A, Valova VA, Larsen MR, Roufogalis BD, Robinson PJ. The brain exocyst complex interacts with RalA in a GTP-dependent manner: Identification of a novel mammalian Sec3 gene and a second Sec15 gene. J Biol Chem. 2001, 276(32), 29792-29797.
18. Powell KA, Valova VA, Malladi CS, Jensen ON, Larsen MR, Robinson PJ. Phosphorylation of Dynamin I on Ser-795 by Protein Kinase C Blocks Its Association With Phospholipids, J Biol Chem 2000, 275(16):11610-7.
17. Larsen MR and Roepstorff P. Mass spectrometric identification of proteins and characterization of their post translational modifications in proteome analysis. Fresenius J Anal Chem, 2000, 366, 677-690.
16. Heegaard NH, Larsen MR, Muncrief T, Wiik A, Roepstorff P. Heterogeneous Nuclear Ribonucleoproteins C1/C2 identified as Autoantigens by Biochemical and Mass Spectrometric Methods. Acthritis Res 2000, 2, 407-414
15. Jellinek DA, Chang AC, Larsen MR, Wang X, Robinson PJ, Reddel RR. Stanniocalcin 1 and 2 are secreted as phosphoproteins from human fibrosarcoma cells. Biochem J 2000, 350(Pt 2):453-461
14. John NE, Andersen HU, Fey SJ, Larsen PM, Roepstorff P, Larsen MR, Pociot F, Karlsen AE, Nerup J, Green IC, Mandrup-Poulsen T. Cytokine or chemically-derived nitric oxide alters the expression of proteins detected by two-dimensional gel electrophoresis in neonatal rat islets of Langerhans. Diabetes. 2000, 49(11), 1819-29.
13. Nouwens AS, Cordwell SJ, Larsen MR, Molloy MP, Gillings M, Willcox MDP and Walsh BJ. Complementing genomics with proteomics: the membrane sub-proteome of Pseudomonas aeruginosa PAO1. Electrophoresis, 2000, 21(17), 3797-3809.
12. Shaw AC, Larsen MR, Roepstorff P, Holm A, Christiansen G, Birkelund S. Mapping and identification of HeLa cell proteins separated by immobilized pH-gradient two-dimensional gel electrophoresis and construction of a 2D-PAGE database. Electrophoresis 1999, 20 No. 4-5, 977-983.
11. Shaw AC, Larsen MR, Roepstorff P, Justesen J, Christiansen G, Birkelund S. Mapping and identification of interferon gamma regulated HeLa cell proteins separated by immobilized pH-gradient two-dimensional gel electrophoresis. Electrophoresis 1999, 20 No. 4-5, 984-993.
10. Byrjalsen I, Mose Larsen P, Fey SJ, Nilas L, Larsen MR, Christiansen C Two-dimensional gel analysis of human endometrial proteins: characterization of proteins with increased expression in hyperplasia and adenocarcinoma. Mol Hum Reprod 1999, (8):748-56
9. Roepstorff, P., Larsen, M.R., Rahbeck-Nielsen, H. and Nordhoff, E.; Sample preparation for matrix assisted laser desorption/ionization mass spectrometry for peptides, protein and nucleic acid, In Cell Biology: A Laboratory Handbook, Second edition, Vol. 4, Academic Press, 1998.
8. Nawrocki, A., Larsen, M.R., Podtelejnikov, A.V., Jensen, O.N., Mann, M., Roepstorff, P., Görg, A., Fey, S.J. and Larsen, P.M.; Correlation of acidic and basic carrier ampholyte and immobilised pH gradient two dimensional gel electrophoresis patterns based on mass spectrometric protein identification, Electrophoresis, 1998, 19, 1024-1035.
7. Jensen ON, Larsen MR, Roepstorff P; Mass spectrometric identification and microcharacterization of proteins from electrophoretic gels: strategies and applications, Proteins: Structure, Function and Genetic, 1998, Suppl 2(1-2), 74-89.
6. Kussmann, M.; Nordhoff, E.; Nielsen, H.R.; Haebel, S.; Larsen, M.R.; Jacobsen, L.; Jensen, C.; Gobom, J.; Mirgorodskaya, E.; Kristensen, A.K., Palm, L. and Roepstorff, P., MALDI-MS sample preparation techniques designed for various peptide and protein analytes, Journal of Mass Spectrometry, 32 (6), 593-601, 1997.
5. Fey, S.J., Nawrocki, A., Larsen, M.R., Görg, A., Roepstorff, P., Skews, G.N., Williams, R. and Larsen, P.M.; Proteome analysis of Saccharomyces cerevisiae: A methodological outline, Electrophoresis, 18, 1361-1372, 1997.
4. Spangfort, M.D.; Ipsen, H.; Sparholt, S.H.; Aasmul-Olsen, S.; Larsen, M.R.; Mörtz, E.; Roepstorff, P. and Larsen, J.N., Characterization of purified recombinant Birch allergen, Bet v 1 with authentic N-terminus, Cloned in Fusion with Maltose-Binding Protein. Protein Expression and Purification, 8, 365-373, 1996.
3. Spangfort MD, Ipsen H, Sparholt SH, Aasmul-Olsen S, Osmark P, Poulsen FM, Larsen M, Mortz E, Roepstorff P, Larsen JN; Characterization of recombinant isoforms of birch pollen allergen Bet v 1. Adv Exp Med Biol, 409, 251-4, 1996
2. Dougherty, L.J.; Brown, E.G.; Gallon, J.R.; Larsen, M.R.; Moertz, E. and Roepstorff, P., Modification of the iron protein of Gloeothece, Nitrogenase: a mass spectrometric study. Biochemical Society Transactions, 24, 477S, 1996.
1. Blomberg, A.; Blomberg, L.; Norbeck, J.; Fey, S.; Larsen, P.M.; Larsen, M.R.; Roepstorff, P.; Degand, H.; Boutry, M.; Posch, A. and Görg, A.: Interlaboratory reproducibility of yeast protein patterns analyzed by immobilized pH gradient two gel electrophoresis. Electrophoresis, 1995, 16, 1935-45.
Thingholm, T.E. and Larsen, M.R. Enrichment and separation of mono- and multi-phosphorylated peptides using Sequential elution from IMAC prior to mass spectrometric analysis. Methods Mol Biol. 2009;527:57-66, xi
Thingholm, T.E., Jensen, O.N. and Larsen, M.R. The use of titanium dioxide micro-columns to selectively isolate phosphopeptides from proteolytic digests. Methods Mol Biol. 2009;527:67-78, xi.
Selby, D.S., Larsen, M.R., Omaetxebarria, M.J. and Roepstorff, P. Sample Preparation for analysis of post-translational modifications – glycosylation. Methods in enzymology. Academic Press. ISSN: 0076-6879. 2008
Larsen, M.R. and Robinson, P.J. Phosphoproteomics. Elsevier, Analytical Chemistry series: Mass Spectrometry of Proteins, 2008. Editor: Julian Whitelegge.
Selby, D.S., Larsen, M.R., Calvano, C.D. and Jensen, O.N. Glycosylation. Methods in Molecular Biology: Functional proteomics. 2008.
Hägglund, P. and Larsen, M.R. Characterization of Glycosylated Proteins Using Micro-Columns, Enzymatic Digestion and Mass Spectrometry. Spectral Techniques in Proteomics, Edition: 1st, 2007. Editor: Sem, Daniel S.
Larsen, M.R., Laugesen, S.V. and Roepstorff, P. Proteome specific sample preparation methods for matrix assisted laser desorption/ionisation mass spectrometry. In Cell Biology: A Laboratory Handbook, Third Edition, Elsevier Science, UK, 2006, edited by Julio E. Celis.
Larsen, M.R. and Jensen, O.N. Post-translational modification of proteins. In Encyclopedia of Genetics, Genomics, Proteomics and Bioinformatics, Wiley, 2005. Editors Michael J. Dunn, Lynn B. Jorde, Peter F. R. Little and Shankar Subramaniam.
Larsen, M.R. Purification of protein and peptide analytes prior to mass spectrometric analysis. Book chapter in “Proteins and Proteomics: A Laboratory Manual” 2004 (Cold Spring Harbor Laboratory Press), pp. 451-462. Editor: Professor Richard Simpson.
Larsen, M.R. Mass spectrometric characterization of post-translationally modified proteins – Phosphorylation. Methods Mol Biol. 2004, 251, 245-62. Human Press, Totowa, New Jersey, Editor: Marie-Isabel Aguilar.