Gougos A, Letarte M
Research Institute, Hospital for Sick Children, Toronto, Canada.
J Biol Chem. 1990 May 25;265(15):8361-4.
Endoglin is a major glycoprotein of human vascular endothelium. As observed with monoclonal antibody 44G4, the distribution of endoglin is restricted to endothelial cells in all tissues except bone marrow. cDNA clones were isolated from an endothelial cell lambda gt11 cDNA library using a rabbit antibody prepared against endoglin purified from placenta. Eleven antibody-positive and cross-hybridizing clones were obtained; reactivity with endothelial cell 3.4-kilobase mRNA transcript was observed. The N-terminal sequence of placental endoglin was determined and found within the deduced protein sequence, thus confirming the identity of the cDNA and revealing a partial signal peptide. Endoglin is a type I integral membrane protein of Mr = 68,051 with an extracellular region of 561 amino acids, a hydrophobic transmembrane domain, and a 47-residue cytoplasmic tail. There are four potential N-linked glycosylation sites in the N-terminal domain and a probable O-glycan domain rich in Ser and Thr residues proximal to the membrane-spanning domain. Data base searches revealed that endoglin is a novel protein. The sequence contains an RGD tripeptide (374-376), the first identified on a surface protein of endothelium. The presence of RGD, a key recognition structure in cellular adhesion, suggests a critical role for endoglin in the binding of endothelial cells to integrins and/or other RGD receptors.
内皮糖蛋白是人类血管内皮细胞的一种主要糖蛋白。正如用单克隆抗体44G4所观察到的，除骨髓外，内皮糖蛋白的分布仅限于所有组织中的内皮细胞。使用针对从胎盘中纯化的内皮糖蛋白制备的兔抗体，从内皮细胞λgt11 cDNA文库中分离出cDNA克隆。获得了11个抗体阳性且交叉杂交的克隆；观察到它们与内皮细胞3.4千碱基mRNA转录本的反应性。确定了胎盘内皮糖蛋白的N端序列，并在推导的蛋白质序列中发现了该序列，从而证实了cDNA的身份并揭示了部分信号肽。内皮糖蛋白是一种Mr = 68,051的I型整合膜蛋白，具有一个由561个氨基酸组成的细胞外区域、一个疏水跨膜结构域和一个47个残基的细胞质尾巴。在N端结构域中有四个潜在的N-连接糖基化位点，并且在跨膜结构域附近有一个富含丝氨酸和苏氨酸残基的可能的O-聚糖结构域。数据库搜索显示内皮糖蛋白是一种新蛋白。该序列包含一个RGD三肽（374-376），这是首次在内皮细胞表面蛋白上鉴定到的。RGD作为细胞黏附中的关键识别结构，其存在表明内皮糖蛋白在内皮细胞与整合素和/或其他RGD受体的结合中起关键作用。
