大鼠子宫内膜促黄体素释放激素(LH—RH)受体及其特性

本文研究结果证明了大鼠子宫内膜有特异的LH-RH结合部位,其亲和常数K_a=1.3×10~8M~(-1),结合位点为236fmole/mg蛋白.在非靶器官组织如肝、肾和肌肉没有结合活性,与其它肽类物质如促甲状腺释放激素(TRH).P物质以及徐缓激肽(BK)未发现有竞争抑制作用.特别有意义的是在妊娠第3天这一临界点,子宫内膜LH-RH结合活性较妊娠第2天和第4天均高,文中对此进行了讨论。     

兔早期胚泡特异肽的cDNA克隆

从家兔受精后第6天(着床前)的早期胚泡构建cDNA文库,经阶段特异分子杂交筛选,克隆了仅在此时期表达的9种胚泡特异肽类的cDNA对其中一种丰度较高的cDNA克隆进行了研究,测出其编码区含有285碱基对,5'和3'侧翼区各有132和170碱基对.经DNA序列分析,推导出一种分泌性多肽的一级结构,由75个氨基酸组成.计算机分析显示它与迄今报道的所有基因和蛋白在结构上无任何同源性.     

胰岛素水溶性受体和膜蛋白的解聚态

胰岛素水溶性受体蛋白和大部分水溶性膜蛋白,在较高浓度的螯合剂或电介质溶液中很易发生可逆的解聚,解聚分子的Stoke半径在22左右,沉降系数1.8—2.8S,据此,解聚的大部分膜蛋白(包括胰岛素受体蛋白)的分子量当在15,000—30,000道尔顿之间,解聚的胰岛素受体仍保留与胰岛素特异结合的活性。     

IDENTIFICATION AND CHARACTERIZATION OF LUTEINIZING HORMONE-RELEASING HORMONE (LH-RH) RECEPTORS IN THE ENDOMETRIAL TISSUE OF PREGNANT RATS

The mechanisms by which LH-RH or its agonists inhibit decidua formation and terminatepregnancy in rats are not clear. Evidence so far accumulated indicates that the gonadotropicreleasing hormone or its analogues may act directly on the uterus. If this is the case, then wewould be able to identify LH-RH receptors in the endometrial tissue. The results presentedhere demonstrate that the homogenate preparation of rat endometrial tissue bound ~125I-LH-RHwith an affinity constant of Ka = 1.3×10~8M~(-1). The binding capacity was measured as 236fmole/mg protein. It was found that the binding is highly specific, because no binding wasobserved in a variety of non-target tissues, such as liver, kidney and muscle. Competitive bind-ing with TRH, P substance and bradykinin did not occur under our experimental condition.It was of particular interest to note that Day 3 of pregnancy is a critical time showing a higherbinding activity. The significance of work is discussed.