Effect of transmembrane Ca2+ gradient on Gs function.
Gs and adenylate cyclase from bovine brain cortices were co-reconstituted into asolectin liposomes with or without 1000-fold transmembrane Ca2+ gradient. Obtained results showed that Gs activities of both binding GTP gamma S and stimulating adenylate cyclase were the highest in proteoliposomes, with a transmembrane Ca2+ gradient similar to the physiological situation and the lowest while the transmembrane Ca2+ gradient was in the inverse direction. Such a difference could be diminished following the dissipation of the transmembrane Ca2+ gradient by A23187. Time-resolved fluorescence anisotropy of diphenylhexatriene (DPH) has been used to compare the physical state of phospholipids among those proteoliposomes. It is suggested that a proper transmembrane Ca2+ gradient is essential for higher membrane fluidity, which may favor Gs function with higher GTP-binding activity and stimulation of adenylate cyclase.
Fan
G F
GF
National Laboratory of Biomacromolecules, Chinese Academy of Sciences, Beijing.
Huang
Y G
YG
Bai
Y H
YH
Yang
F Y
FY
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism; D005454:Fluorescence Polarization; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D008081:Liposomes; D008560:Membrane Fluidity; D010713:Phosphatidylcholines; D010743:Phospholipids / Q000378:metabolism
D008081:Liposomes; D010713:Phosphatidylcholines; D010743:Phospholipids; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C024990:asolectin; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D002118:Calcium