Andersen P H, Nielsen M
Department of Pharmacology, NOVO Industri A/S, Pharmaceuticals, R&D, Bagsvaerd, Denmark.
Neurosci Lett. 1987 Dec 16;83(1-2):167-72. doi: 10.1016/0304-3940(87)90235-7.
In frozen rat striatal tissue, exposed to 10 MeV electrons from a linear accelerator, the sizes of the dopamine (DA) D1 receptor and the DA-sensitive adenylate cyclase complex were determined using target size analysis. The number of D1 receptors (labelled by [3H]SCH 23390) declined monoexponentially with increasing radiation intensity, yielding a molecular weight (mol.wt.) of 80 kDa. Also the activity of the catalytic unit (C) of the adenylate cyclase (as measured by forskolin stimulation), decreased monoexponentially, however with a mol.wt. of 145 kDa. Both basal, DA- and fluoride (F-)-stimulated activity declined in a concave-downward fashion with a limiting mol.wt. of 134, 138 and 228 kDa, respectively. It was estimated that the basal and DA-stimulated activity originated from an enzyme complex with a mol.wt. of 325 kDa, a value close to the combined size of RGs and C. These data suggest that F- stimulation of the adenylate cyclase, which occurs by a Gs activation, does not cause dissociation of Gs into the alpha s and beta gamma subunits. Further, the DA-regulated adenylate cyclase apparently exists as a complex consisting of RGs and C; the mechanism of hormonal activation is a dissociation of C from this complex.
在暴露于直线加速器产生的10兆电子伏特电子的冷冻大鼠纹状体组织中，使用靶标大小分析法测定了多巴胺（DA）D1受体和DA敏感腺苷酸环化酶复合物的大小。D1受体（用[3H]SCH 23390标记）的数量随着辐射强度的增加呈单指数下降，得出分子量（mol.wt.）为80 kDa。腺苷酸环化酶催化单位（C）的活性（通过福司可林刺激测量）也呈单指数下降，但其分子量为145 kDa。基础活性、DA刺激活性和氟化物（F-）刺激活性均呈向下凹陷的方式下降，其极限分子量分别为134、138和228 kDa。据估计，基础活性和DA刺激活性源自分子量为325 kDa的酶复合物，该值接近调节蛋白（RGs）和C的组合大小。这些数据表明，通过Gs激活发生的腺苷酸环化酶的F-刺激不会导致Gs解离为αs和βγ亚基。此外，DA调节的腺苷酸环化酶显然以由RGs和C组成的复合物形式存在；激素激活的机制是C从该复合物中解离。
