title: The side chain of glutamine 13 is the acyl-donor amino acid modified by type 2 transglutaminase in subunit T of the native rabbit skeletal muscle troponin complex.
abstract: Subunit T of the native muscle troponin complex is a recognised substrate of transglutaminase both in vitro and in situ with formation of isopeptide bonds. Using a proteomic approach, we have now determined the precise site of in vitro labelling of the protein. A preparation of troponin purified from ether powder from mixed rabbit skeletal muscles was employed as transglutaminase substrate. The only isoform TnT2F present in our preparation was recognised as acyl-substrate by human type 2 transglutaminase which specifically modified glutamine 13 in the N-terminal region. During the reaction, the troponin protein complex was polymerized. Results are discussed in relation to the structure of the troponin T subunit, in the light of the role of troponins in skeletal and cardiac muscle diseases, and to the rules governing glutamine side chain selection by tissue transglutaminase.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Ferrara, Via Borsari 46, 44121 Ferrara, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Squerzanti
authors.forename: Carlo
authors.initials: C
authors.lastname: Cervellati
authors.forename: Blendi
authors.initials: B
authors.lastname: Ura
authors.forename: Carlo
authors.initials: C
authors.lastname: Mischiati
authors.forename: Piero
authors.initials: P
authors.lastname: Pucci
authors.forename: Stefano
authors.initials: S
authors.lastname: Annunziata
authors.forename: Carla
authors.initials: C
authors.lastname: Iannone
authors.forename: Rita
authors.initials: R
authors.lastname: Casadio
authors.forename: Carlo M
authors.initials: CM
authors.lastname: Bergamini
authors.forename: Carla
authors.initials: C
authors.lastname: Esposito
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000737:chemistry; D017124:Conserved Sequence; D004912:Erythrocytes / Q000201:enzymology; D019204:GTP-Binding Proteins; D005973:Glutamine / Q000737:chemistry*; D006801:Humans; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011499:Protein Processing, Post-Translational; D021122:Protein Subunits / Q000737:chemistry; D011817:Rabbits; D020539:Sequence Analysis, Protein; D013096:Spermine / Q000737:chemistry; D011503:Transglutaminases / Q000737:chemistry*; D020107:Troponin T / Q000737:chemistry*
chemical_list: D021122:Protein Subunits; D020107:Troponin T; D005973:Glutamine; D013096:Spermine; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins; D002118:Calcium