Hormonal control of protein phosphorylation in turkey erythrocytes. Phosphorylation by cAMP-dependent and Ca2+-dependent protein kinases of distinct sites in goblin, a high molecular weight protein of the plasma membrane.

摘要: In previous studies, a correlation was observed between isoproterenol-responsive Na+-K+ co-transport in turkey erythrocytes and increased phosphorylation of goblin, an Mr = 230,000 protein the erythrocyte plasma membrane. The specific sites goblin has now been analyzed by tryptic fingerprinting. Three major phosphopeptides were detected prepared from intact, 32P-labeled erythrocytes. One peptides 1, maximally phosphorylated absence hormonal agents. Two additional peptides, 2 3, only following exposure cells to beta-adrenergic agonist isoproterenol, cAMP plus isobutylmethylxanthine, or cholera toxin. stimulated 3 could be selectively completely reversed subsequent addition antagonist propranolol. Addition either Ca2+ calmodulin purified membranes incorporation 32P into goblin. Peptides cAMP-dependent kinase. 4 5, membrane preparation Ca2+, whereas not under these conditions. Peptide 1 did incorporate any condition tested. Both kinase identified directly three intact (peptides 2, 3) contained phosphothreonine represented distinct sites. contrast, two Ca+/calmodulin 5) phosphoserine. It is concluded that possibly involved regulation co-transport, contains at least threonine residues more serine which serve as substrates for kinases erythrocyte, namely enzyme, Ca2+/calmodulin-dependent third enzyme with undetermined regulatory control.