title: Characterization of a 54-kilodalton human protein kinase recognized by an antiserum raised against the myotonin kinase.
abstract: We characterized a 54-kDa human protein kinase recognized by an antiserum raised against the human myotonin protein kinase. This protein kinase displays a serine/threonine kinase activity in the heart and a tyrosine kinase activity in the skeletal muscle. Both kinase activities were attributed to the same 54-kDa protein based on the identity of one-dimensional peptide maps. We showed that the tyrosine kinase activity observed in the skeletal muscle results from a phosphorylation of this protein kinase on tyrosine residues by a tyrosine kinase specifically expressed in this tissue. The tyrosine dephosphorylation of the skeletal muscle 54-kDa protein kinase allowed it to phosphorylate with the highest activity the same peptide substrates as those phosphorylated by the human recombinant myotonin kinase. These results show that a muscle-specific tyrosine phosphorylation event converts a serine/threonine kinase to a tyrosine kinase. They also suggest that the 54-kDa protein kinase is a member of the myotonin kinase family.
authors.affiliation: Department of Human Genetics, CHU Laval Research Center, Ste-Foy, Quebec, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Etongué-Mayer
authors.forename: R
authors.initials: R
authors.lastname: Faure
authors.forename: J P
authors.initials: JP
authors.lastname: Bouchard
authors.forename: J
authors.initials: J
authors.lastname: Puymirat
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D018482:Muscle, Skeletal / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology*; D065636:Myotonin-Protein Kinase; D010449:Peptide Mapping; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D011494:Protein Kinases / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011817:Rabbits; D011994:Recombinant Proteins / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D000906:Antibodies; C585517:DMPK protein, human; D010455:Peptides; D011994:Recombinant Proteins; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases