Phorbol esters promote α1-adrenergic receptor phosphorylation and receptor uncoupling from inositol phospholipid metabolism
DDT1 MF-2 cells, which are derived from hamster vas deferens smooth muscle, contain α1-adrenergic receptors (54,800 ± 2700 sites per cell) that are coupled to stimulation of inositol phospholipid metabolism. Incubation of these cells with tumor-promoting phorbol esters, which stimulate calcium- and phospholipid-dependent protein kinase, leads to a marked attenuation of the ability of α1-receptor a