Théoleyre M, Bérault A, Garnier J, Jutisz M
Mol Cell Endocrinol. 1976 Oct;5(5):365-77. doi: 10.1016/0303-7207(76)90019-8.
Specific binding studies of tritium-labeled LH-RH to sheep anterior pituitary membranes at 37 degrees C showed a maximum of binding capacity of 110 +/- 20 mol/mg protein with an association rate constant of 2 +/- 1 X 10(5) M-1 S-1 and a dissociation rate constant of 0.7 +/- 0.4 X 10(-2) S-1. The Scatchard plot data showed a single type of binding site with Kass = 1.1 +/- 0.4 X 10(8) M-1 in good agreement with the kinetic studies. Various doses of LH-RH in the presence or absence of Ca2+, were unable to stimulate adenylate cyclase either in the rat anterior pituitary homogenates, or in the purified sheep anterior pituitary plasma membranes. To explain these results, it may be argued that the proportion of gonadotrophs in the pituitary gland is too small to show a significant increase in the LH-RH-induced adenylate cyclase activity. Another possibility is the disconnection of the hormonal receptor from the site of activation of adenylate cyclase during the preparation of plasma membranes. Finally, cAMP may not be involved in LH release by LH-RH.
在37摄氏度下，对氚标记的促黄体生成激素释放激素（LH-RH）与绵羊垂体前叶膜进行的特异性结合研究表明，其最大结合容量为110±20摩尔/毫克蛋白质，缔合速率常数为2±1×10⁵M⁻¹S⁻¹，解离速率常数为0.7±0.4×10⁻²S⁻¹。斯卡查德图数据显示存在单一类型的结合位点，其平衡解离常数Kass = 1.1±0.4×10⁸M⁻¹，这与动力学研究结果高度吻合。无论有无Ca²⁺存在，各种剂量的LH-RH均无法刺激大鼠垂体前叶匀浆或纯化的绵羊垂体前叶质膜中的腺苷酸环化酶。为了解释这些结果，可以认为垂体中促性腺细胞的比例过小，以至于LH-RH诱导的腺苷酸环化酶活性无法显著增加。另一种可能性是在质膜制备过程中，激素受体与腺苷酸环化酶的激活位点发生了解离。最后，环磷酸腺苷（cAMP）可能不参与LH-RH诱导的促黄体生成素（LH）释放。
