Modular mutagenesis of human placental ribonuclease inhibitor, a protein with leucine-rich repeats.-猫眼课题宝

人胎盘核糖核酸酶抑制剂的模块化诱变，一种富含亮氨酸重复序列的蛋白质。

DOI：

10.1073/pnas.87.5.1879

发表时间：

1990

期刊：

Proceedings of the National Academy of Sciences of the United States of America

影响因子：

11.1

通讯作者：

中科院分区：

综合性期刊1区

文献类型：

作者：

F. Lee;B. Vallée

Human placental ribonuclease inhibitor (PRI) is a potent protein inhibitor of pancreatic ribonucleases and the homologous blood vessel-inducing protein angiogenin. Although inhibition by PRI occurs with a 1:1 stoichiometry, its primary structure is composed predominantly of seven internal leucine-rich repeats. These internal repeats were systematically deleted either singly or in combination by "modular" mutagenesis. Deletion of repeat units 3 plus 4 or repeat unit 6 results in mutants that both bind to and inhibit ribonuclease A. Therefore, the angiogenin/ribonuclease binding site in PRI must reside primarily or entirely in repeats 1, 2, 5, or 7, the short N- or C-terminal segments, or a combination of these. Deletion of repeat units 3-5, 5-6, or 5 alone results in mutants that exhibit only binding activity. Hence, the binding site cannot reside exclusively in repeat 5. Other internal deletions or N- or C-terminal deletions of 6-86% of the protein all abolish activity. These results suggest that PRI has a modular structure, with one primary structural repeat constituting one module. The approach taken may be applicable to other proteins with repeat structures.