Activated Gs or its alpha subunit directly prolonged the survival of excised calcium channels and stimulated the activity of incorporated channels, independently of cytoplasmic kinases.
Do G proteins directly regulate mammalian cardiac calcium channels?
Demonstrates that G proteins can directly gate mammalian cardiac calcium channels, independent of cytoplasmic kinase activation.
A possible direct effect of guanine nucleotide binding (G) proteins on calcium channels was examined in membrane patches excised from guinea pig cardiac myocytes and bovine cardiac sarcolemmal vesicles incorporated into planar lipid bilayers. The guanosine triphosphate analog, GTP gamma S, prolonged the survival of excised calcium channels independently of the presence of adenosine 3',5'-monophosphate (cAMP), adenosine triphosphate, cAMP-activated protein kinase, and the protein kinase C activator tetradecanoyl phorbol acetate. A specific G protein, activated Gs, or its alpha subunit, purified from the plasma membranes of human erythrocytes, prolonged the survival of excised channels and stimulated the activity of incorporated channels. Thus, in addition to regulating calcium channels indirectly through activation of cytoplasmic kinases, G proteins can regulate calcium channels directly. Since they also directly regulate a subset of potassium channels, G proteins are now known to directly gate two classes of membrane ion channels.
Yatani et al. (Fri,) reported a other. GTP gamma S and activated Gs or its alpha subunit was evaluated on Survival of excised calcium channels and activity of incorporated channels. Activated Gs or its alpha subunit directly prolonged the survival of excised calcium channels and stimulated the activity of incorporated channels, independently of cytoplasmic kinases.