title: Catalytic fragment of protein kinase C exhibits altered substrate specificity toward smooth muscle myosin light chain.
abstract: Smooth muscle myosin light chain (LC) can be phosphorylated by myosin light chain kinase (MLCK) at Ser19 and Thr18 and by protein kinase C (PKC) at Thr9 and Ser1 or Ser2 under the in vitro assay conditions. Conversion of PKC to the spontaneously active protein kinase M (PKM) by proteolysis resulted in a change in the substrate specificity of the kinase. PKM phosphorylated both sets of sites in LC recognized by MLCK and PKC as analyzed by peptide mapping analysis. The PKM-catalyzed phosphorylation of these sites was not greatly affected by a MLCK inhibitor, ML-9, nor by the activators of MLCK, Ca2+ and calmodulin.
authors.affiliation: Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: H
authors.initials: H
authors.lastname: Nakabayashi
authors.forename: J R
authors.initials: JR
authors.lastname: Sellers
authors.forename: K P
authors.initials: KP
authors.lastname: Huang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D015180:Electrophoresis, Gel, Two-Dimensional; D005895:Gizzard, Avian / Q000378:metabolism; D007525:Isoelectric Focusing; D007700:Kinetics; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000378:metabolism*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D009218:Myosins / Q000378:metabolism*; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D010449:Peptide Mapping; D011493:Protein Kinase C / Q000378:metabolism*; D013379:Substrate Specificity; D014357:Trypsin; D014422:Turkeys
chemical_list: D010446:Peptide Fragments; D011493:Protein Kinase C; D009219:Myosin-Light-Chain Kinase; D014357:Trypsin; D009218:Myosins