The functional significance of the last 5 residues of the C-terminus of cardiac troponin i

Jennifer E. Gilda, Qian Xu, Margaret E. Martinez, Susan T. Nguyen, P. Bryant Chase, Aldrin V Gomes

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

The C-terminal region of cardiac troponin I (cTnI) is known to be important in cardiac function, as removal of the last 17 C-terminal residues of human cTnI has been associated with myocardial stunning. To investigate the C-terminal region of cTnI, three C-terminal deletion mutations in human cTnI were generated: Δ1 (deletion of residue 210), Δ3 (deletion of residues 208-210), and Δ5 (deletion of residues 206-210). Mammalian two-hybrid studies showed that the interactions between cTnI mutants and cardiac troponin C (cTnC) or cardiac troponin T (cTnT) were impaired in Δ3 and Δ5 mutants when compared to wild-type cTnI. Troponin complexes containing 2-[4′-(iodoacetamido) anilino] naphthalene-6-sulfonic acid (IAANS) labeled cTnC showed that the troponin complex containing cTnI Δ5 had a small increase in Ca2+ affinity (P < 0.05); while the cTnI Δ1- and Δ3 troponin complexes showed no difference in Ca2+ affinity when compared to wild-type troponin. In vitro motility assays showed that all truncation mutants had increased Ca2+ dependent motility relative to wild-type cTnI. These results suggest that the last 5 C-terminal residues of cTnI influence the binding of cTnI with cTnC and cTnT and affect the Ca2+ dependence of filament sliding, and demonstrate the importance of this region of cTnI.

Original languageEnglish (US)
Pages (from-to)88-96
Number of pages9
JournalArchives of Biochemistry and Biophysics
Volume601
DOIs
StatePublished - Jul 1 2016

Keywords

  • Calcium
  • Heart
  • In vitro motility assay
  • Mammalian two-hybrid
  • Troponin I
  • Unloaded filament sliding

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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