Pertussis toxin distinguishes between muscarinic receptor‐mediated inhibition of adenylate cyclase and stimulation of phosphoinositide hydrolysis in Flow 9000 cells

[摘要]

Pretreatment of human embryonic pituitary tumour cells (Flow 9000) with pertussis toxin significantly reduced carbachol-mediated inhibition of isoprenaline and prostaglandin E₂ stimulation of cyclic AMP formation. This is in accord with an action on the inhibitory G_i-protein by pertussis toxin. In contrast, pertussis toxin-pretreatment had no effect on either muscarinic agonist or GTP[S] (a non-hydrolysable GTP analogue) stimulation of [³H]inositol phosphate production in intact and permeabilized [³H]inositol-prelabelled Flow 9000 cells, respectively. These results suggest that muscarinic receptors are linked to the inhibition of adenylate cyclase and the stimulation of phosphoinositidase C via two different G-proteins in Flow 9000 cells.

[学科分类] 生物化学/生物物理

[关键词] G-protein;Muscarinic receptor;Pertussis toxin;Inositol phosphate;cyclic AMP;(Flow 9000 cell);G-proteins;guanine nucleotide-binding proteins;Gi;inhibitory G-protein;[3H]IP;total [3H]inositol phosphates;PI;polyphosphoinositides;GTP[S];guanosine 5′-O-(thiotriphosphate)