The presence but not the sequence of the N‐terminal peptide in cardiac TnC is important for function

FEBS Letters

Lin, Xin¹  Gonzalez-Garay, Manuel L.¹  Putkey, John A.¹  Lu, Qingxian¹  Mullen, James J.¹  Dotson, Darrell G.¹  Liu, Wen¹ 

[1] Department of Biochemistry and Molecular Biology, The University of Texas Medical School 6431 Fannin, Houston, TX 77030, USA

关键词: Cardiac troponin C;    Muscle regulation;    Mutagenesis;   

DOI  :  10.1016/0014-5793(94)00526-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The most diverged region of the primary amino acid sequence between cardiac (cTnC) and fast skeletal troponin C is the N-terminal ten amino acids. We report here that major changes in the primary sequence of this region in cTnC had a minimal effect on the ability of the mutant proteins to recover maximal activity in TnC-extracted cardiac and fast skeletal muscle myofibrils. However, deletion of the N-terminal nine amino acids resulted in a 60% decrease in maximal Ca²⁺-dependent ATPase activity with only a small change in the pCa₅₀ of activation. Deletion of the N-terminal peptide did not appear to appreciably affect the Ca²⁺-binding properties of cTnC, but it did alter the interaction with hydrophobic fluorescent probes. Thus, the presence but not the sequence, of the N-terminal extension is important for the maximal activity of cTnC. The N-terminal helix may function in a relatively non-specific manner to prevent unfavorable interactions between domains in cTnC or between cTnC and other troponin subunits.

【 授权许可】

Unknown