Abstract
Isoproterenol incubated with turkey erythrocyte membranes causes exposure of a specific -SH in a component associated with the β-adrenergic receptor, presumably in the guanyl nucleotide binding protein. Addition of a reagent which interacts with that specific -SH results in trapping of the hormone in the receptor. As a consequence, the number of hormone binding sites and the function of the receptor are both drastically reduced. Extended incubation at alkaline pH or addition of GDP or GTP at high concentration reactivate the β-adrenergic receptor. Labeled antagonist binding as well as function of the receptor in activating an adenylate cyclase system are restored. The findings suggest that the normal interaction of the hormonereceptor complex with the guanyl necleotide binding protein involves a conformational change which transiently locks the hormone in the receptor. GTP releases the tight interaction while addition of an-SH reagent traps the ternary complex of hormone-receptor-guanyl nucleotide binding protein in the locked conformation. Since the components of different hormone-activated adenylate cyclase systems were shown to be interchangeable, it seems likely that the hormone-receptor interaction with the guanyl nucleotide binding protein, as revealed in the present study, is not limited to β-adrenergic receptor systems.
Original language | English |
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Pages (from-to) | 3389-3396 |
Number of pages | 8 |
Journal | Journal of Biological Chemistry |
Volume | 257 |
Issue number | 7 |
State | Published - 1982 |