Hori H, Yoshino T, Ishizuka Y, Yamauchi T, Shiratori Y, Nakagawa S, Umeyama H, Murakami K
Institute of Applied Biochemistry, University of Tsukuba, Ibaraki, Japan.
Clin Exp Hypertens A. 1988;10(6):1147-55. doi: 10.1080/07300077.1988.11878807.
To study the role of N-linked oligosaccharides attached to human renin, we generated three kinds of glycosylation-deficient renins in which one or both of two putative N-glycosylation sites was eliminated by amino acid replacement using site-directed mutagenesis. Examination of the three mutant renins (Asn-5 to Ala, Asn-75 to Ala, and both Asn-5 and -75 to Ala) expressed in COS cells demonstrated that both putative sites were certainly glycosylated with heterologous N-linked oligosaccharides. Moreover, the oligosaccharide chain attached at Asn-5 was different from that attached at Asn-75 in its molecular size. In addition, the secreted amount of the three mutant renins were different from one another, although the mutant and wild-type renins had practically the same specific activity. Our results suggest that the N-linked oligosaccharides have no effect on the enzymatic activity, but play an important role in stable secretion of human renin.
为了研究与人类肾素相连的N-连接寡糖的作用，我们利用定点诱变通过氨基酸置换产生了三种糖基化缺陷型肾素，其中两个假定的N-糖基化位点中的一个或两个被消除。对在COS细胞中表达的三种突变型肾素（天冬酰胺-5突变为丙氨酸、天冬酰胺-75突变为丙氨酸以及天冬酰胺-5和-75均突变为丙氨酸）的检测表明，两个假定位点确实都被异源N-连接寡糖糖基化。此外，连接在天冬酰胺-5上的寡糖链在分子大小上与连接在天冬酰胺-75上的不同。另外，尽管突变型和野生型肾素具有几乎相同的比活性，但三种突变型肾素的分泌量彼此不同。我们的结果表明，N-连接寡糖对酶活性没有影响，但在人类肾素的稳定分泌中起重要作用。
