Expression and characterization of recombinant beta-subunit hCG homodimer.
Expression and characterization of recombinant beta-subunit hCG homodimer.
复制标题
重组 β 亚基 hCG 同二聚体的表达和表征。
DOI：
10.1007/bf02738625
复制
发表时间：
1999
期刊：
影响因子：
3.7
通讯作者：
Lustbader,JW
中科院分区：
文献类型：
--
作者：
Lobel,L;Pollak,S;Wang,S;Chaney,M;Lustbader,JW
我们将两个人绒毛膜促性腺激素（hCG）β亚基cDNA串联，使表达的融合蛋白由两个成熟的β亚基组成，通过第一个β亚基的羧基末端肽连接。在融合蛋白的两个亚基之间插入单个甘氨酸残基。用含有融合cDNA的克隆转化的中国仓鼠卵巢（CHO）细胞表达并分泌一种蛋白质，该蛋白质与β-hCG同源二聚体蛋白一致。这些β-同二聚体分子可以与两个游离的α-亚基重组，表明同二聚体内的两个β-亚基可能以其天然构象折叠。我们的数据还表明，这两个β亚基作为一个球状蛋白相互折叠，而不是作为两个线性β亚基的简单融合体存在。此外，融合蛋白中的两个β-单体亚基形成了一个稳定的同源二聚体，可以特异性地结合并激活hLH/CG受体。融合蛋白与α-亚基的结合似乎有利于两个α-亚基联合收割机与融合蛋白的单个分子结合的排列。重组分子由四个亚基组成，相当于两个拴系的hCG部分，构成hCG二聚体。这种激素二聚体可以结合并激活hLH/CG受体，其活性接近天然hCG。
We have linked two human chrionic gonadotropin (hCG) β-subunit cDNAs in tandem such that the expressed fusion protein consists of two mature β-subunits joined through the carboxy terminal peptide of the first β-subunit. A single glycine residue is inserted between the two subunits in the fusion protein. Chinese hamster ovary (CHO) cells transformed with a clone that contains the fused cDNAs express and secrete a protein that is consistent with it being a β-hCG homodimer protein. These β-homodimer molecules can recombine with two free α-subunits indicating that both β-subunits within the homodimer are likely folded in their native conformation. Our data also suggest that the two β-subunits fold upon each other as a globular protein and do not appear to exist as a simple fusion of two linear β-subunits. Further-more, the two β-monomer subunits in the fusion protein form a stable homodimer that can bind and activate the hLH/CG receptor specifically. Recombination of the fusion protein with α-subunits appears to favor an arrangement where two α-subunits combine with a single molecule of the fusion protein. The recombined molecule consists of four subunits and is comparable to two tethered hCG moieties, which constitutes a hCG dimer. This hormone dimer can bind and activate the hLH/CG receptor with an activity approximating that of native hCG.