Properties of protein kinases in brain coated vesicles.
Coated vesicles prepared from bovine brain contained cyclic nucleotides- and Ca2+-calmodulin-independent protein kinases which in the presence of Mg2+ catalyzed the phosphorylation of an endogenous 48,000 Mr protein of coated vesicles (C-48), phosvitin and troponin T. Phosvitin was phosphorylated either in the presence of ATP or GTP. The phosphorylation of C-48, on the other hand, was specific for ATP. Heparin inhibited the phosphorylation of phosvitin but not that of C-48. Mn2+ inhibited the phosphorylation of phosvitin, while Mn2+ substituted for Mg2+ in the phosphorylation of C-48. When the coated vesicles were prepared in the presence of NaF, C-48 contained 2.5-2.8 mol of phosphate/mol. On incubation with Mg2+ and ATP, C-48 incorporated 1.2-1.6 mol of phosphate/mol. With C-48 as a substrate, the value of its apparent Km for ATP was 6 microM. With phosvitin as a substrate, the value of its apparent Km was 20 microM. The phosphorylated amino acid residues in the phosvitin were identified as serine and threonine. Phosphothreonine was detected in C-48. These results suggest that brain coated vesicles possess two different classes of protein kinase, a casein kinase II and C-48 kinase.
Takahashi
A
A
Usami
M
M
Kadota
T
T
Kadota
K
K
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002417:Cattle; D003034:Coated Pits, Cell-Membrane / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006493:Heparin / Q000494:pharmacology; D007700:Kinetics; D008345:Manganese / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D010774:Phosvitin / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D012492:Salts / Q000494:pharmacology; D013379:Substrate Specificity; D014336:Troponin / Q000378:metabolism; D020107:Troponin T
D008565:Membrane Proteins; D012492:Salts; D014336:Troponin; D020107:Troponin T; D008345:Manganese; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D006493:Heparin; D010774:Phosvitin; D011494:Protein Kinases