title: Myelin basic protein, an autoantigen in multiple sclerosis, is selectively processed by human trypsin 4.
abstract: Demyelination, the proteolytic degradation of the major membrane protein in central nervous system, myelin, is involved in many neurodegenerative diseases. In the present in vitro study the proteolytic actions of calpain, human trypsin 1 and human trypsin 4 were compared on lipid bound and free human myelin basic proteins as substrates. The fragments formed were identified by using N-terminal amino acid sequencing and mass spectrometry. The analysis of the degradation products showed that of these three proteases human trypsin 4 cleaved myelin basic protein most specifically. It selectively cleaves the Arg79-Thr80 and Arg97-Thr98 peptide bonds in the lipid bound form of human myelin basic protein. Based on this information we synthesized peptide IVTPRTPPPSQ that corresponds to sequence region 93-103 of myelin basic protein and contains one of its two trypsin 4 cleavage sites, Arg97-Thr98. Studies on the hydrolysis of this synthetic peptide by trypsin 4 have confirmed that the Arg97-Thr98 peptide bond is highly susceptible to trypsin 4. What may lend biological interest to this finding is that the major autoantibodies found in patients with multiple sclerosis recognize sequence 85-96 of the protein. Our results suggest that human trypsin 4 may be one of the candidate proteases involved in the pathomechanism of multiple sclerosis.
authors.affiliation: Department of Biochemistry, Eötvös Loránd University, Pázmány Péter st. 1/C, H-1117 Budapest, Hungary.
authors.forename: Péter
authors.initials: P
authors.lastname: Medveczky
authors.forename: József
authors.initials: J
authors.lastname: Antal
authors.forename: András
authors.initials: A
authors.lastname: Patthy
authors.forename: Katalin
authors.initials: K
authors.lastname: Kékesi
authors.forename: Gábor
authors.initials: G
authors.lastname: Juhász
authors.forename: László
authors.initials: L
authors.lastname: Szilágyi
authors.forename: László
authors.initials: L
authors.lastname: Gráf
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens / Q000235:genetics / Q000378:metabolism*; D002154:Calpain / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D004676:Myelin Basic Protein; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014357:Trypsin / Q000235:genetics / Q000378:metabolism*; D014362:Trypsinogen / Q000378:metabolism
chemical_list: D001324:Autoantigens; C499048:MBP protein, human; D004676:Myelin Basic Protein; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D020033:Protein Isoforms; D014157:Transcription Factors; D014362:Trypsinogen; C489303:PRSS1 protein, human; C040749:PRSS3 protein, human; D014357:Trypsin; D002154:Calpain