Evidence for stimulation of adenylyl cyclase by an activated G(s) heterotrimer in cell membranes: an experimental method for controlling the G(s) subunit composition of cell membranes.

Heterotrimeric (alphabetagamma) G(s) mediates agonist-induced stimulation of adenylyl cyclase (AC). Cholera toxin (CTx) will ADP-ribosylate the alpha-subunit of G(s) (G(s)alpha). G(s)alpha-deficient cyc(-) membranes were "stripped" of Gbeta.

Chloride effects on Gs subunit dissociation. Fluoroaluminate binding to Gs does not cause subunit dissociation in the absence of chloride ion.

The stimulatory guanine nucleotide binding protein (Gs) is heterotrimeric ( alpha beta gamma), and mediates activation of adenylyl cyclase by a ligand-receptor complex. The alpha subunit of Gs (Gsalpha) has a guanine nucleotide binding site, and activation occurs when tightly bound GDP is displaced by GTP. Together, GDP and fluoroaluminate (AlF4-) form a transition state analog of GTP that activates Gs.

Choleragen catalyzes ADP-ribosylation of the stimulatory G protein heterotrimer but not its free alpha-subunit.

The heterotrimeric (alpha beta gamma) stimulatory G protein (Gs) mediates activation of adenylylcyclase. Gs is inactive when GDP is bound to the guanine nucleotide binding site of the alpha-subunit (Gs alpha). Gs can be activated by fluoroaluminate or by binding GTP or GTP analogues, (e.

Demonstration of two distinct insulin-binding components in solubilized human placental membranes by radioimmunoassay using synthetic peptide and anti-synthetic peptide antibody.

A peptide corresponding to the 957-980 sequence of human placental insulin receptor precursor (HIRP) was synthesized and antisera were produced against the synthetic peptide. Anti-synthetic HIRP(957-980) serum HIR-27 was proved to cross-react with HIRP-related proteins in solubilized human placental membranes. A radioimmunoassay developed with the antiserum and synthetic peptide HIRP(957-980) enabled us to separate, in combination with gel filtration, two insulin-binding components in solubilized human placental membranes which conceivably correspond to the alpha 2 beta 2 and alpha beta structures of the placental insulin receptor.