Structural details of a calcium-induced molecular switch: X-ray crystallographic analysis of the calcium-saturated N-terminal domain of troponin C at 1.75 angstrom resolution

被引:107
作者
Strynadka, NCJ [1 ]
Cherney, M [1 ]
Sielecki, AR [1 ]
Li, MX [1 ]
Smillie, LB [1 ]
James, MNG [1 ]
机构
[1] UNIV ALBERTA, DEPT BIOCHEM, MRC, GRP PROT STRUCT & FUNCT, EDMONTON, AB T6G 2H7, CANADA
基金
英国医学研究理事会;
关键词
Ca2+-binding protein; X-ray crystallography; conformational change; muscle contraction; Ca2+-ligands;
D O I
10.1006/jmbi.1997.1257
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
We have solved and refined the crystal and molecular structures of the calcium-saturated N-terminal domain of troponin C (TnC) to 1.75 Angstrom resolution. This has allowed for the first detailed analysis of the calcium binding sites of this molecular switch in the calcium-loaded state. The results provide support for the proposed binding order and qualitatively, for the affinity of calcium in the two regulatory calcium binding sites. Based on a comparison with the high-resolution ape-form of TnC we propose a possible mechanism for the calcium-mediated exposure of a large hydrophobic surface that is central to the initiation of muscle contraction within the cell. (C) 1997 Academic Press Limited.
引用
收藏
页码:238 / 255
页数:18
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