Evidence that (a) serine specific protein kinase(s) different from protein kinase C is responsible for the insulin-stimulated actin phosphorylation by placental membrane.
Partially purified phospholipid- and Ca2+-dependent protein kinase C from human placenta catalyzes the Mg-ATP-dependent phosphorylation of serine residues of purified rabbit muscle actin. Two tryptic [32P]-phosphopeptides were found on HPLC separation. Confirming the previous report by Machicao and Wieland [(1985) Curr. Top. Cell. Regul. 27, 95-105], actin is phosphorylated at serine residues by human placental membranes, and this is stimulated by insulin. In the absence of insulin trypsin treatment yielded eight [32P]phosphopeptides, two of which coincided with the ones due to protein kinase C. Insulin led to the appearance of three new [32P]phosphopeptides. These results suggest that insulin stimulates (a) serine protein kinase(s) which, like protein kinase C, is present in placental membranes.
D000199:Actins / Q000378:metabolism*; D002122:Calcium Chloride / Q000494:pharmacology; D002413:Cations, Divalent; D002462:Cell Membrane / Q000201:enzymology; D004075:Diglycerides / Q000494:pharmacology; D005260:Female; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D010718:Phosphatidylserines / Q000494:pharmacology; D010766:Phosphorylation; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D011493:Protein Kinase C / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases
D000199:Actins; D002413:Cations, Divalent; D004075:Diglycerides; D007328:Insulin; D010718:Phosphatidylserines; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D008274:Magnesium; D002122:Calcium Chloride; C013965:diolein