Regulation of human platelet adenylate cyclase by epinephrine, prostaglandin E1, and guanine nucleotides. Evidence for separate guanine nucleotide sites mediating stimulation and inhibition.
Regulation of human platelet adenylate cyclase by epinephrine, prostaglandin E1, and guanine nucleotides. Evidence for separate guanine nucleotide sites mediating stimulation and inhibition.
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肾上腺素、前列腺素 E1 和鸟嘌呤核苷酸对人血小板腺苷酸环化酶的调节。
DOI：
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发表时间：
1979
影响因子：
4.8
通讯作者：
A. Wood
中科院分区：
文献类型：
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作者：
M. Steer;A. Wood
本发明描述了一种制备具有高腺苷酸环化酶活性的人血小板膜的方法。使用这些膜，注意到肾上腺素和GTP单独地轻微抑制腺苷酸环化酶。当一起存在时，肾上腺素和GTP协同作用，导致基础活性抑制50%。肾上腺素效应是一种α-肾上腺素能过程，因为它可以被酚妥拉明逆转，但不能被普萘洛尔逆转。Gpp（NH）p对腺苷酸环化酶的准不可逆激活是时间、浓度和Mg 2+依赖性的，但不因肾上腺素的存在而改变。由Gpp（NH）p激活并充分洗涤以除去未结合的Gpp（NH）p的腺苷酸环化酶被随后加入的Gpp（NH）p、GTP和肾上腺素抑制。肾上腺素的这种作用也是一种α-肾上腺素能现象。与抑制环化酶的肾上腺素相反，加入PGE 1导致酶刺激。PGE 1刺激不需要添加GTP。PGE 1加速Gpp（NH）p诱导的活化的速率。低浓度的GTP（低于1 × 10（-6）M）可增强PGE 1的刺激作用，而高浓度的GTP则会导致抑制作用。这些观察结果表明，人血小板腺苷酸环化酶具有至少两个鸟嘌呤核苷酸位点，一个与α-受体相互作用以导致酶抑制，第二个鸟嘌呤核苷酸位点与PGE 1受体相互作用并引起酶刺激。
A method for preparing human platelet membranes with high adenylate cyclase activity is described. Using these membranes, epinephrine and GTP individually are noted to inhibit adenylate cyclase slightly. When present together, epinephrine and GTP act synergistically to cause a 50% inhibition of basal activity. The epinephrine effect is an alpha-adrenergic process as it is reversed by phentolamine but not propranolol. The quasi-irreversible activation of adenylate cyclase by Gpp(NH)p is time, concentration, and Mg2+-dependent but is not altered by the presence of epinephrine. Adenylate cyclase activated by Gpp(NH)p, and extensively washed to remove unbound Gpp(NH)p, is inhibited by the subsequent addition of Gpp(NH)p, GTP, and epinephrine. This effect of epinephrine is also an alpha-adrenergic phenomenon. In contrast to epinephrine which inhibits the cyclase, PGE1 addition results in enzyme stimulation. PGE1 stimulation does not require GTP addition. PGE1 accelerates the rate of Gpp(NH)p-induced activation. Low GTP concentrations (less than 1 x 10(-6) M) enhance PGE1 stimulation while higher GTP concentrations cause inhibition. These observations suggest that human platelet adenylate cyclase possesses at least two guanine nucleotide sites, one which interacts with the alpha-receptor to result in enzyme inhibition and a second guanine nucleotide site which interacts with the PGE1 receptor and causes enzyme stimulation.