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Effect of transmembrane Ca 2+ gradient on G s function
Author(s) -
Fan Gao-feng,
Huang You-guo,
Bai Yan-hong,
Yang Fu-yu
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)01307-m
Subject(s) - diphenylhexatriene , transmembrane protein , chemistry , electrochemical gradient , cyclase , gtp' , adenylate kinase , biophysics , transmembrane domain , fluorescence anisotropy , biochemistry , membrane , biology , receptor , enzyme
G s and adenylate cyclase from bovine brain cortices were co‐reconstituted into asolectin liposomes with or without 1000‐fold transmembrane Ca 2+ gradient. Obtained results showed that G s activities of both binding GTPγS and stimulating adenylate cyclase were the highest in proteoliposomes, with a transmembrane Ca 2+ gradient similar to the physiological situation and the lowest while the transmembrane Ca 2+ gradient was in the inverse direction. Such a difference could be diminished following the dissipation of the transmembrane Ca 2+ 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 Ca 2+ gradient is essential for higher membrane fluidity, which may favor G s function with higher GTP‐binding activity and stimulation of adenylate cyclase.