A phospholipid is the membrane-anchoring domain of a protein growth factor of molecular mass 34 kDa in placental trophoblasts.
A phospholipid is the membrane-anchoring domain of a protein growth factor of molecular mass 34 kDa in placental trophoblasts.
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磷脂是胎盘滋养层中分子量为 34 kDa 的蛋白质生长因子的膜锚定结构域。
DOI：
10.1073/pnas.85.6.2014
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发表时间：
1988
影响因子：
11.1
通讯作者：
Das,M
中科院分区：
文献类型：
--
作者：
Roy-Choudhury,S;Mishra,VS;Low,MG;Das,M
最近，我们从人胎盘滋养层细胞膜中分离到一种分子量为34 kDa的蛋白质生长因子。膜结合34-kDa蛋白的一部分（约等于50%）是外周结合的-即，它可以通过高盐处理来释放。其余部分显示了完整膜蛋白的特征，即，其释放需要洗涤剂处理。在这里，我们报告的蛋白质的膜锚定的结构基础上的研究。磷脂酶C被发现从完整的分离的细胞滋养层细胞释放免疫反应性34 kDa的多肽。分离的滋养层膜的研究表明，磷脂酶C特异性释放的34 kDa的多肽的耐盐部分。磷脂酶C释放的多肽在NaDodSO 4/PAGE中显示出与磷脂酶C处理前的多肽相同的电泳迁移率。释放的蛋白质与34-kDa的生长因子的身份已经建立了免疫和受体结合试验。其他研究表明，存在[3 H]肉豆蔻酸酯生物合成掺入到34-kDa蛋白中。肉豆蔻酸酯标记物对磷脂酶C处理不稳定。这些结果表明，一些34-kDa的蛋白质是锚定到质膜通过postpertinationally添加磷脂。这种模式的锚定已被观察到的一些其他的膜蛋白，并提出了有趣的问题，这种新的连接在促有丝分裂功能的34-kDa的多肽的作用。
Recently we isolated a protein growth factor of 34 kDa from trophoblastic membranes of human placenta. A fraction (approximately equal to 50%) of the membrane-associated 34-kDa protein is peripherally associated--i.e., it can be released by high salt treatment. The remainder shows the characteristics of an integral membrane protein--i.e., its release requires detergent treatment. Here we report studies on the structural basis for membrane anchorage of the protein. Phospholipase C was found to release an immunoreactive 34-kDa polypeptide from intact isolated cytotrophoblasts. Studies with isolated trophoblastic membranes showed that phospholipase C specifically released the salt-resistant fraction of the 34-kDa polypeptide. The polypeptide released by phospholipase C showed the same electrophoretic mobility in NaDodSO4/PAGE as the polypeptide prior to phospholipase C treatment. The identity of the released protein with the 34-kDa growth factor has been established by both immunologic and receptor-binding assays. Other studies show that there is biosynthetic incorporation of [3H]myristate into the 34-kDa protein. The myristate label is labile to phospholipase C treatment. These results suggest that some of the 34-kDa protein is anchored to the plasma membrane via a posttranslationally added phospholipid. This mode of anchorage has been observed for some other membrane proteins and raises interesting questions regarding the role of this novel linkage in the mitogenic function of the 34-kDa polypeptide.