Abramson S N, Martin M W, Hughes A R, Harden T K, Neve K A, Barrett D A, Molinoff P B
Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia 19104-6084.
Biochem Pharmacol. 1988 Nov 15;37(22):4289-97. doi: 10.1016/0006-2952(88)90609-0.
beta-Adrenergic receptors on membranes prepared from L6 myoblasts, wild-type S49 lymphoma cells, and an adenylate cyclase-deficient variant (cyc-) of S49 lymphoma cells bind the agonist [3H]hydroxybenzylisoproterenol ([3H]HBI) with high affinity. In each case the agonist [3H]HBI is associated with a larger complex than is the antagonist [125I]iodopindolol, and the binding of [3H]HBI can be inhibited by GTP. These observations suggest that there is an agonist-dependent association of the receptor with a guanine nucleotide-binding protein. The goal of the present experiments was to investigate the possibility that an interaction of beta-adrenergic receptors with the inhibitory guanine nucleotide-binding protein of adenylate cyclase was responsible for these observations. Treatment of S49 cells with pertussis toxin decreased the extent of pertussis toxin-catalyzed [32P]ADP-ribosylation of a 41,000-dalton protein, measured in vitro, and decreased the inhibition of adenylate cyclase activity observed in the presence of somatostatin or analogues of GTP. Isoproterenol-stimulated adenylate cyclase activity was potentiated following treatment of wild-type S49 cells and L6 myoblasts with pertussis toxin. Although the ability of receptors on membranes prepared from L6 myoblasts to bind the agonist [3H]HBI was not affected by treatment of cells with pertussis toxin, treatment of cyc- S49 cells with pertussis toxin markedly decreased the ability of receptors to bind [3H]HBI. The observed inhibition of the binding of the agonist [3H]HBI to beta-adrenergic receptors on membranes prepared from cyc- S49 cells after treatment with pertussis toxin could be explained by an interaction between beta-adrenergic receptors and the inhibitory guanine nucleotide-binding protein. Such an interaction may represent a mechanism through which stimulation of the activity of adenylate cyclase by beta-adrenergic receptors can be regulated or through which beta-adrenergic receptors can affect the activity of cyclic AMP-independent cellular processes.
从L6成肌细胞、野生型S49淋巴瘤细胞以及S49淋巴瘤细胞的腺苷酸环化酶缺陷变体（cyc-）制备的细胞膜上的β-肾上腺素能受体，能以高亲和力结合激动剂[3H]羟基苄基异丙肾上腺素（[3H]HBI）。在每种情况下，激动剂[3H]HBI与比拮抗剂[125I]碘吲哚洛尔更大的复合物相关联，并且[3H]HBI的结合可被GTP抑制。这些观察结果表明，受体与鸟嘌呤核苷酸结合蛋白存在激动剂依赖性关联。本实验的目的是研究β-肾上腺素能受体与腺苷酸环化酶的抑制性鸟嘌呤核苷酸结合蛋白的相互作用是否是这些观察结果的原因。用百日咳毒素处理S49细胞，降低了体外测量的41,000道尔顿蛋白的百日咳毒素催化的[32P]ADP-核糖基化程度，并降低了在生长抑素或GTP类似物存在下观察到的腺苷酸环化酶活性的抑制。用百日咳毒素处理野生型S49细胞和L6成肌细胞后，异丙肾上腺素刺激的腺苷酸环化酶活性增强。虽然用百日咳毒素处理细胞不会影响从L6成肌细胞制备的细胞膜上的受体结合激动剂[3H]HBI的能力，但用百日咳毒素处理cyc-S49细胞会显著降低受体结合[3H]HBI的能力。用百日咳毒素处理后，观察到激动剂[3H]HBI与cyc-S49细胞制备的细胞膜上的β-肾上腺素能受体的结合受到抑制，这可以通过β-肾上腺素能受体与抑制性鸟嘌呤核苷酸结合蛋白之间的相互作用来解释。这种相互作用可能代表了一种机制，通过该机制β-肾上腺素能受体对腺苷酸环化酶活性的刺激可以受到调节，或者β-肾上腺素能受体可以影响不依赖环磷酸腺苷的细胞过程的活性。
