The smg GDS-induced activation of smg p21 is initiated by cyclic AMP-dependent protein kinase-catalyzed phosphorylation of smg p21.
We have shown that smg p21B is phosphorylated by cyclic AMP-dependent protein kinase (protein kinase A) and that membrane acidic phospholipids such as phosphatidic acid and phosphatidylinositol markedly inhibit the smg GDS-induced activation of smg p21B. However, we show here that phosphatidic acid and phosphatidylinositol exhibit a less inhibitory effect on the smg GDS-induced activation of the phosphorylated form of smg p21B. Thus, in the presence of membrane acidic phospholipids, the smg GDS-induced activation of smg p21B is totally dependent on the protein kinase A-catalyzed phosphorylation of smg p21B. Since smg p21B is located on the membranes in resting cells, it is likely that the smg GDS-induced activation of smg p21B is initiated by the protein kinase A activation.
Itoh
T
T
Department of Biochemistry, Kobe University School of Medicine, Japan.
Kaibuchi
K
K
Sasaki
T
T
Takai
Y
Y
D000818:Animals; D001685:Biological Factors / Q000378:metabolism*; D001792:Blood Platelets / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D009132:Muscles / Q000201:enzymology; D010712:Phosphatidic Acids / Q000494:pharmacology*; D010716:Phosphatidylinositols / Q000494:pharmacology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D011817:Rabbits; D020668:rap GTP-Binding Proteins
D001685:Biological Factors; D010712:Phosphatidic Acids; D010716:Phosphatidylinositols; D011518:Proto-Oncogene Proteins; D011494:Protein Kinases; D019204:GTP-Binding Proteins; D020668:rap GTP-Binding Proteins