鸟苷三磷酸（GTP）调节[125I]碘褪黑素与叙利亚仓鼠下丘脑皮摩尔亲和力位点的结合。

GTP modulates [125I]iodomelatonin binding to a picomolar-affinity site in the Syrian hamster hypothalamus.

作者信息

Niles L P

机构信息

Department of Biomedical Sciences, McMaster University, Ontario, Canada.

出版信息

Eur J Pharmacol. 1990 Jul 31;189(1):95-8. doi: 10.1016/0922-4106(90)90234-o.

DOI:10.1016/0922-4106(90)90234-o

PMID:2226639

Abstract

Saturation binding experiments conducted with [125I]iodomelatonin at 0-4 degrees C in the Syrian hamster hypothalamus, revealed a single nanomolar-affinity site which was not affected by GTP. In contrast, incubation at 30 degrees C revealed two distinct binding sites with picomolar and nanomolar affinities, respectively. GTP caused a significant decrease in the affinity of only the picomolar site but did not alter its density; control: Kd = 43 +/- 6 pM, Bmax = 1.7 +/- 0.3 fmol/mg protein; GTP (1 mM): Kd = 250 +/- 52, Bmax = 3.9 +/- 2.6 fmol/mg protein. The foregoing indicates that the affinity of the putative melatonin receptor in the hamster hypothalamus is modulated by a regulatory G protein.

摘要

在0 - 4摄氏度下，用[125I]碘褪黑素对叙利亚仓鼠下丘脑进行饱和结合实验，结果显示存在一个不受GTP影响的纳摩尔亲和力位点。相比之下，在30摄氏度下孵育则显示出两个分别具有皮摩尔和纳摩尔亲和力的不同结合位点。GTP仅使皮摩尔位点的亲和力显著降低，但不改变其密度；对照组：解离常数（Kd）= 43 ± 6皮摩尔，最大结合容量（Bmax）= 1.7 ± 0.3飞摩尔/毫克蛋白；GTP（1毫摩尔）：Kd = 250 ± 52，Bmax = 3.9 ± 2.6飞摩尔/毫克蛋白。上述结果表明，仓鼠下丘脑假定的褪黑素受体的亲和力受一种调节性G蛋白调控。