Lee Y L, Hintz R L, James P M, Lee P D, Shively J E, Powell D R
Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77054.
Mol Endocrinol. 1988 May;2(5):404-11. doi: 10.1210/mend-2-5-404.
The primary structure of an insulin-like growth factor (IGF) binding protein produced by human HEP G2 hepatoma cells has been deduced from the cDNA sequence. The 234 amino acid protein has a predicted molecular mass of 25,274 and contains a single, distinctive cysteine-rich region. The N-terminal sequence of this protein is quite similar to the limited sequence data available for a rat IGF binding protein produced by BRL-3A cells and suggests a common ancestral origin. In contrast, the HEP G2 IGF binding protein sequence bears no similarity to the N-terminal 15 amino acids of a 53 kilodalton binding protein purified from human plasma. Comparison of full-length protein sequences for the IGF-I and IGF-II receptors with that of the HEP G2 IGF binding protein also fails to demonstrate any significant similarities among these three proteins, and suggests that each contains a unique binding domain for the IGF peptides.
人肝癌细胞系HEP G2产生的胰岛素样生长因子（IGF）结合蛋白的一级结构已根据cDNA序列推导出来。这种由234个氨基酸组成的蛋白质预计分子量为25,274，并且包含一个独特的富含半胱氨酸区域。该蛋白的N端序列与BRL-3A细胞产生的大鼠IGF结合蛋白的有限序列数据非常相似，提示有共同的祖先起源。相比之下，HEP G2 IGF结合蛋白序列与从人血浆中纯化的53千道尔顿结合蛋白的N端15个氨基酸没有相似性。将IGF-I和IGF-II受体的全长蛋白序列与HEP G2 IGF结合蛋白的序列进行比较，也未显示这三种蛋白之间有任何显著相似性，提示每种蛋白都含有一个独特的IGF肽结合结构域。
