Biologically important interactions between synthetic peptides of the N-terminal region of troponin I and troponin C.
The interaction between troponin I and troponin C plays a critical role in the regulation of muscle contraction. In this study the interaction between troponin C (TnC) and the N-terminal region of TnI was investigated by the synthesis of three TnI peptides (residues 1-40/Rp, 10-40, and 20-40). The regulatory peptide (Rp) on binding to TnC prevents the ability of TnC to release the inhibition of the acto-S1-tropomyosin ATPase activity caused by TnI or the TnI inhibitory peptide (Ip), residues 104-115. A stable complex between TnC and Rp in the presence of Ca2+ was demonstrated by polyacrylamide gel electrophoresis in the presence of 6 M urea. Rp was able to displace TnI from a preformed TnI.TnC complex. In the absence of Ca2+, Rp was unable to maintain a complex with TnC in benign conditions of polyacrylamide gel electrophoresis which demonstrates the Ca(2+)-dependent nature of this interaction. Size-exclusion chromatography demonstrated that the TnC.Rp complex consisted of a 1:1 complex. The results of these studies have shown that the N-terminal region of TnI (1-40) plays a critical role in modulating the Ca(2+)-sensitive release of TnI inhibition by TnC.
Ngai
S M
SM
Department of Biochemistry, University of Alberta, Edmonton, Canada.
Hodges
R S
RS
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D007700:Kinetics; D008969:Molecular Sequence Data; D009132:Muscles / Q000378:metabolism; D010455:Peptides / Q000138:chemical synthesis / Q000378:metabolism*; D011485:Protein Binding; D011817:Rabbits; D014336:Troponin / Q000138:chemical synthesis / Q000378:metabolism*; D019209:Troponin C; D019210:Troponin I
D000199:Actins; D010455:Peptides; D014336:Troponin; D019209:Troponin C; D019210:Troponin I