Two phosphorylations specific to the tail region of the 204-kDa heavy chain isoform of porcine aorta smooth muscle myosin.
In a porcine aorta extract, we observed two protein kinase activities which specifically phosphorylate the 204-kDa heavy chain isoform of aorta myosin in the absence of conventional kinase activators. We referred to these two protein kinases, eluted at 0.15 and 0.2 M KCl from a DEAE-column, as myosin kinases I (MKI) and II (MKII), respectively. The phosphorylation site for MKI was determined using a purified phosphopeptide derived from porcine aorta myosin phosphorylated with MKI. By comparison with the deduced amino acid sequence for smooth muscle myosins, the site corresponded to a Ser located at 3 amino acids upstream from a Pro, the putative end of the alpha-helical segment of the 204-kDa heavy chain tail. A homologous Ser is only present in smooth muscle myosins, i.e. not in nonmuscle myosins. MKI was purified 130-fold, but not separated from a kinase activity phosphorylating Ser1 or Ser2 in the 20-kDa regulatory light chain of aorta myosin. In contrast, MKII was purified to near homogeneity. MKII phosphorylated the porcine aorta myosin heavy chain at a Ser 19 amino acids downstream from the MKI site. The amino acid sequence around the Ser shared a consensus sequence of the phosphorylation site. The amino acid sequence around the Ser shared a consensus sequence of the phosphorylation site for casein kinase II and was homologous to that reported for bovine aorta myosin [Kelley, C.A. and Adelstein, R.S. (1990) J Biol. Chem. 265, 17876-17882]. MKII was identified as a multifunctional protein kinase, casein kinase II.
Fukui
Y
Y
Division of Chemistry, Graduate School of Science, Hokkaido University.
Morita
F
F
D000135:Acid Phosphatase; D000595:Amino Acid Sequence; D000818:Animals; D001011:Aorta; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D047390:Casein Kinase II; D002417:Cattle; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000737:chemistry / Q000378:metabolism*; D018994:Myosin Light Chains / Q000378:metabolism; D010449:Peptide Mapping; D010748:Phosphopeptides / Q000032:analysis; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D015800:Protozoan Proteins; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000378:metabolism; D013379:Substrate Specificity; D013552:Swine
D018994:Myosin Light Chains; D010748:Phosphopeptides; D015800:Protozoan Proteins; D012694:Serine; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C033142:myosin-heavy-chain kinase; D000135:Acid Phosphatase; D018995:Myosin Heavy Chains