LH-RH binding to purified pituitary plasma membranes: Absence of adenylate cyclase activation
LH-RH binding to purified pituitary plasma membranes: Absence of adenylate cyclase activation
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LH-RH 与纯化的垂体质膜结合：缺乏腺苷酸环化酶激活
DOI：
10.1016/0303-7207(78)90033-3
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发表时间：
1978
影响因子：
4.1
通讯作者：
J. Marshall
中科院分区：
文献类型：
--
作者：
R. Clayton;R. Shakespear;J. Marshall
纯化的牛垂体质膜具有两个特定的 LH-RH 结合位点。高亲和力位点 (2.5 × 109l/mol) 具有较低的容量 (9 × 10−1.5mol/mg 膜蛋白)，而低亲和力位点 (6.1 × 105l/mol) 具有更高的容量 (1.1 × 10−10mol/mg)。在从匀浆纯化过程中，与质膜的特异性 LH-RH 结合增加了 8.5 倍，而腺苷酸环化酶活性则丰富了 7-8 倍。与蔗糖密度梯度界面部分结合的特异性 LH-RH 的分布与腺苷酸环化酶活性的分布平行。 Mg2+ 和 Ca2+ 在微摩尔浓度下抑制特异性 [125I]LH-RH 结合。合成的 LH-RH，高达 250 μg/ml，无法刺激纯化牛膜的腺苷酸环化酶活性。使用粗制的 10,800grat 垂体膜制剂，即使在鸟苷酸存在下，LH-RH 同样也无法激活腺苷酸环化酶。这些数据证实了垂体质膜上 LH-RH 受体位点的存在，并表明 LH-RH 诱导的促性腺激素释放可能是由腺苷酸环化酶激活以外的机制介导的。
Purified bovine pituitary plasma membranes possess two specific LH-RH binding sites. The high affinity site (2.5 × 109l/mol) has low capacity (9 × 10−1.5mol/mg membrane protein) while the low affinity site (6.1 × 105l/mol) has a much higher capacity (1.1 × 10−10mol/mg). Specific LH-RH binding to plasma membranes is increased 8.5-fold during purification from homogenate whilst adenylate cyclase activity is enriched 7–8-fold. Distribution of specific LH-RH binding to sucrose density gradient interface fractions parallels that of adenylate cyclase activity. Mg2+and Ca2+inhibit specific [125I]LH-RH binding at micromolar concentrations.Synthetic LH-RH, up to 250 μg/ml, failed to stimulate adenylate cyclase activity of the purified bovine membranes. Using a crude 10,800grat pituitary membrane preparation, LH-RH similarly fails to activate adenylate cyclase even in the presence of guanyl nucleotides.These data confirm the presence of LH-RH receptor sites on pituitary plasma membranes and suggest that LH-RH-induced gonadotrophin release may be mediated by mechanisms other than activation of adenylate cyclase.