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Regulation of Adenylate Cyclase Activity by a GTP-Binding Peptida in Rat Liver.

GTP 结合肽对大鼠肝脏中腺苷酸环化酶活性的调节。

基本信息

批准号：
63570105
负责人：
OMORI Kyoko
金额：
$ 1.34万
依托单位：
Kansai Medical University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1990
项目状态：
已结题

项目摘要

A cytosolic peptide ・ GTP complex which stimulates iota -isoproterenol- responsive adenylate cyclase activity was identified in the rat liver. The peptide component was purified and characterized with regard to its interaction with GTP in the regulation of adenylate cyclase. The peptide was isolated as a complex form with GTP on a Sephadex G-25 column in 1 mM NaHCO_3, and on the same column in 200 mM ammonium acetate it was purified as a dissociated form with Mr -3,000. The purified peptide alone displayed a markedly decreased stimulatory effect on adenylate cyclase activity, but its reassociated form with GTP clearly enhanced the effect of GTP on the enzyme activity. The isoproterenol competition curve using iota -[^3H]dihydroalprenolol (DHA) as an antagonist ligand shifted to lower affinity by the addition of the peptide reassociated with GTP (16.5-fold shift), while the same concentration of GTP (1 mu M) or the peptide alone had little or no effect (1.5- or 0.9-fold shift, respectively). Furthermore, the peptide enhanced the GTP effect in the response to iota -isoproterenol but not in that to glucagon, prostaglandin E_1 and fluoride. These results suggest that the peptide component of the cytosolic activator potentiates the effect of GTP on the agonist- beta -adrenergic receptor-stimulatory guanine nucleotide-binding regulatory component of adenylate cyclase (G_s) (GDP) ternary complex.

在大鼠肝脏中发现了一种胞质肽·GTP复合物，它能刺激iota -异丙肾上腺素应答腺苷酸环化酶的活性。对肽组分进行了纯化，并对其与GTP在调节腺苷酸环化酶中的相互作用进行了表征。在1 mM NaHCO_3溶液中，用Sephadex G-25色谱柱分离GTP，在200 mM乙酸铵溶液中，用Mr - 3000分离GTP。纯化后的肽对腺苷酸环化酶活性的刺激作用明显降低，但与GTP的再结合形式明显增强了GTP对酶活性的影响。以iota -[^3H]二氢丙烯诺尔（DHA）为拮抗剂配体的异丙肾上腺素竞争曲线在加入与GTP重新相关的肽后（16.5倍位移）向低亲和力方向移动，而相同浓度的GTP （1 μ M）或单独的肽几乎没有影响（分别为1.5倍或0.9倍位移）。此外，肽增强了GTP对iota -异丙肾上腺素的作用，而对胰高血糖素、前列腺素E_1和氟化物的作用没有增强。这些结果表明，胞浆激活剂的肽组分增强了GTP对腺苷酸环化酶（G_s）（GDP）三元复合物的激动剂- β -肾上腺素能受体-刺激鸟嘌呤核苷酸结合调节组分的作用。