The beta adrenergic receptor binding sites of turkey erythrocyte membranes, identified by (-)-[3H]dihydroalprenolol binding, were solubilized with digitonin. The binding sites in particulate and soluble preparations displayed appropriate characteristics of beta1 adrenergic specificity, stereospecificity, high affinity and saturability. The affinity of all agonists tested was significantly (2-50-fold) greater in the soluble than in the particulate preparations. The affinities of antagonists, however, were identical in the soluble and particulate preparations. Agonist-specific alterations in receptor binding affinity were also found to be mediated by assay temperature. Thus agonist but not antagonist affinities increased as the temperature was lowered from 37° to 4°. Possible molecular mechanisms responsible for the observed shifts are discussed.
|Number of pages||6|
|State||Published - Jan 1 1978|