REDUCED NUMBER AND COUPLING OF BETA-ADRENERGIC RECEPTORS IN A MODIFIED S-49 MOUSE LYMPHOMA CELL-LINE

Long-term culture of S-49 wild-type cells in medium containing a high concentration of fetal calf serum leads to a modified (S-49 m) cell li ne with a reduced number of beta-adrenergic receptors (R). These S-49 m cells with a higher rate of proliferation were unable to respond to the beta-adrenergic agonists isoproterenol (ISO) and epinephrine as an alysed by measuring adenylate cyclase (ac) activity on purified membra nes of these cells. Additionally, no accumulation of cyclic AMP was ob tained on S-49 m intact cells upon stimulation with beta-agonists. Nev ertheless, S-49 m cells were able to respond significantly to the dire ct activation of the stimulatory guanine nucleotide binding (G(s)) pro tein by aluminium tetrafluoride and sodium fluoride, and to the stimul ation of another receptor coupled to the ac system through a G(s) prot ein, by prostaglandin E(1) (PGE(1)). When cloning S-49 m cells, simila r results were obtained upon stimulation with ISO and PGE(1) and the c loned cells express the same thy 1.2 and class Id molecules as do S-49 cells. The study of S-49 m cells indicates that they are a beta-adren ergic R-deficient variant distinct from the other variants described f or S-49 cells.