Speth R C, Mei L, Yamamura H I
Dept. VCAPP, Washington State University, Pullman 99164-6520.
Pept Res. 1989 May-Jun;2(3):232-9.
NG108-15 cells were grown in culture to confluency and membranes were prepared from the cells to test for the presence of angiotensin II (Ang II) receptors using 125I-sarcosine1, isoleucine8 angiotensin II (125I-SI Ang II). These radioligand binding studies indicated a single class of binding sites with high affinity (KD = 221 +/- 54 pM) that were saturable (Bmax = 27.2 +/- 1.6 fmol/mg protein) and showed characteristic specificity (SI Ang II greater than Ang II greater than Sar1Thr8 Ang II greater than Ang III greater than Ang I greater than des Phe8 Ang II greater than des Asp1, Arg2, Val3 pentapeptide Ang II). To see if these putative receptor binding sites were associated with a functional response, the effect of Ang II on phosphatidylinositide (PtdIns) hydrolysis, expressed as inositol monophosphate (IP1) formation in intact NG108-15 cells preloaded with 3H-myoinositol, was determined. Ang II inhibited IP1 formation up to 35% below the basal rate in a dose related manner. The inhibition of PtdIns hydrolysis was prevented by pre-exposure of the cells to SI Ang II, an Ang II receptor antagonist. These results indicate that undifferentiated NG108-15 cells possess Ang II receptors that mediate a reduction in PtdIns hydrolysis.
将NG108 - 15细胞培养至汇合状态，然后从细胞中制备细胞膜，使用125I - 肌氨酸1、异亮氨酸8血管紧张素II（125I - SI Ang II）检测血管紧张素II（Ang II）受体的存在。这些放射性配体结合研究表明存在一类具有高亲和力（KD = 221±54 pM）的结合位点，这些位点具有饱和性（Bmax = 27.2±1.6 fmol/mg蛋白质），并表现出特征性的特异性（SI Ang II＞Ang II＞Sar1Thr8 Ang II＞Ang III＞Ang I＞去苯丙氨酸8 Ang II＞去天冬氨酸1、精氨酸2、缬氨酸3五肽Ang II）。为了观察这些假定的受体结合位点是否与功能反应相关，测定了Ang II对磷脂酰肌醇（PtdIns）水解的影响，以预先加载3H - 肌醇的完整NG108 - 15细胞中肌醇单磷酸（IP1）的形成来表示。Ang II以剂量相关的方式抑制IP1的形成，使其比基础速率低35%。预先将细胞暴露于Ang II受体拮抗剂SI Ang II可防止PtdIns水解的抑制。这些结果表明，未分化的NG108 - 15细胞具有介导PtdIns水解减少的Ang II受体。
