Coupling of glucagon receptor to adenylyl cyclase. Requirement of a receptor-related guanyl nucleotide binding site for coupling of receptor to the enzyme.
Coupling of glucagon receptor to adenylyl cyclase. Requirement of a receptor-related guanyl nucleotide binding site for coupling of receptor to the enzyme.
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胰高血糖素受体与腺苷酸环化酶的偶联。
DOI：
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发表时间：
1979
影响因子：
4.8
通讯作者：
L. Birnbaumer
中科院分区：
文献类型：
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作者：
R. Iyengar;T. Swartz;L. Birnbaumer
研究了胰高血糖素和鸟苷核苷酸对大鼠肝细胞质膜腺酰环化酶的影响。已证实：1)高血糖素刺激完全鸟氨酰-5‘-亚胺二磷酸(GMP-P(NH)P)激活的酶的比例在20%到70%之间，前提是检测中存在鸟苷核苷酸；2)在被GMP-P(NH)P完全激活然后洗去核苷酸的膜上，胰高血糖素对腺苷环化酶活性没有影响。结果表明，激活该体系催化部分的鸟苷核苷酸结合部位的占据不足以促进激素受体与腺苷环化酶的偶联，而鸟嘌呤核苷酸占据第二位点对胰升糖素-受体复合体对腺酰环化酶的刺激是必不可少的。这些数据提出了一个问题，即促进偶联的鸟苷核苷酸位点是否不同于调节胰高血糖素与受体结合的鸟苷核苷酸位点，以及与催化部分相关的鸟苷核苷酸位点的占位是否是偶联所必需的。
Effects of glucagon and guanyl nucleotides on the rat liver plasma membrane adenylyl cyclase were studied. It was established that: 1) glucagon stimulates the fully guanyl-5'-yl imidodiphosphate (GMP-P(NH)P)-activated enzyme between 20 and 70%, provided a guanyl nucleotide is present in the assay; 2) glucagon has no effect on adenylyl cyclase activity in membranes activated fully by GMP-P(NH)P and then washed free of nucleotides. It is concluded that occupancy of the guanyl nucleotide binding site that activates the catalytic moiety of the system is not sufficient to promote hormone-receptor coupling to adenylyl cyclase and that occupancy of a second site by guanyl nucleotides is essential to effect stimulation of adenylyl cyclase by the glucagon-receptor complex. The data presented raise the question whether the guanyl nucleotide site that promotes coupling is distinct from the guanyl nucleotide site that modulates binding of glucagon to receptor and whether the occupancy of the guanyl nucleotide site associated with the catalytic moiety is necessary for coupling.