胰岛素样生长因子结合蛋白（IGFBP）-2和-3的钙蛋白酶解作用，但不包括IGFBP-1的钙蛋白酶解作用。

Calpain proteolysis of insulin-like growth factor binding protein (IGFBP) -2 and -3, but not of IGFBP-1.

作者信息

Berg Ulrika, Bang Peter, Carlsson-Skwirut Christine

机构信息

Department of Woman and Child Health, Pediatric Endocrinology and Diabetes Unit, Karolinska Institute, Astrid Lindgren Children's Hospital, S-171 76 Stockholm, Sweden.

出版信息

Biol Chem. 2007 Aug;388(8):859-63. doi: 10.1515/BC.2007.098.

DOI:10.1515/BC.2007.098

PMID:17655506

Abstract

Calpains are cytoplasmic Ca(2+)-regulated cysteine proteases that may regulate insulin-like growth factor (IGF)-independent actions of insulin-like growth factor binding proteins (IGFBPs) through IGFBP proteolysis. In this study, [(125)I]-labeled IGFBP-2 and -3, but not IGFBP-1, were proteolyzed by Ca(2+)-activated m-calpain in vitro. Degradation of higher concentrations of the recombinant proteins IGFBP-2 and -3 by m-calpain was dose-dependent, but was terminated within 20 min by autolysis. By subjecting proteolytic fragments to N-terminal amino acid sequence analysis, the primary cleavage sites in IGFBP-2 and -3 were localized to the non-conserved central linker regions. Using the biosensor technique, in vitro binding of m-calpain to IGFBP-3 was demonstrated to be a Ca(2+)-dependent reaction with a rapid on/off rate.

摘要

钙蛋白酶是一种受细胞质钙离子调节的半胱氨酸蛋白酶，它可能通过胰岛素样生长因子结合蛋白（IGFBPs）的蛋白水解作用来调节胰岛素样生长因子（IGF）非依赖性的胰岛素样生长因子结合蛋白的作用。在本研究中，[125I]标记的IGFBP-2和-3，而非IGFBP-1，在体外被钙离子激活的m-钙蛋白酶进行了蛋白水解。m-钙蛋白酶对较高浓度的重组蛋白IGFBP-2和-3的降解呈剂量依赖性，但在20分钟内会因自身水解而终止。通过对蛋白水解片段进行N端氨基酸序列分析，IGFBP-2和-3中的主要切割位点定位于非保守的中央连接区。利用生物传感器技术，证明m-钙蛋白酶与IGFBP-3的体外结合是一种钙离子依赖性反应，其结合和解离速度都很快。