Characterisation of a mutant of barnacle troponin C lacking Ca2+- binding sites at positions II and IV

L. D. Allhouse, G. Guzman, T. Miller, Q. Li, J. D. Potter, C. C. Ashley

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

This study investigates a mutant barnacle troponin C (TnC) protein (BTnC2-4-) in which the Ca2+binding sites (sites II and IV) have been rendered non-functional. Eliminating Ca2+ binding at both Ca2+-binding sites of barnacle TnC did not prevent the incorporation of BTnC2-4- into TnC- depleted myofibrillar bundles, although, as expected, the mutant was not able to effect muscle regulation. We conclude that the Mg2+ involved in stabilising the interaction between TnC and TnI in the barnacle must bind at a separate location to the Ca2+-binding sites. Competition experiments between BTnC2-4- and wild-type barnacle TnC (BTnCWT) or the native isoform BTnC2 indicate that BTnC2-4- has an approximately fourfold higher affinity for barnacle TnI than BTnCWT but a lower affinity for TnI compared to BTnC2. These results indicate that disabling sites II and IV changes the affinity of BTnC2-4- for TnC-denuded barnacle myofibrils, altering the stability of the bond formed between TnC and the thin filament.

Original languageEnglish
Pages (from-to)30-39
Number of pages10
JournalPflugers Archiv European Journal of Physiology
Volume438
Issue number1
DOIs
StatePublished - Jun 7 1999
Externally publishedYes

Fingerprint

Thoracica
Troponin C
Binding Sites
Myofibrils
Muscle
Protein Isoforms
Muscles

Keywords

  • Calcium
  • Muscle
  • Troponin C

ASJC Scopus subject areas

  • Physiology

Cite this

Characterisation of a mutant of barnacle troponin C lacking Ca2+- binding sites at positions II and IV. / Allhouse, L. D.; Guzman, G.; Miller, T.; Li, Q.; Potter, J. D.; Ashley, C. C.

In: Pflugers Archiv European Journal of Physiology, Vol. 438, No. 1, 07.06.1999, p. 30-39.

Research output: Contribution to journalArticle

Allhouse, L. D. ; Guzman, G. ; Miller, T. ; Li, Q. ; Potter, J. D. ; Ashley, C. C. / Characterisation of a mutant of barnacle troponin C lacking Ca2+- binding sites at positions II and IV. In: Pflugers Archiv European Journal of Physiology. 1999 ; Vol. 438, No. 1. pp. 30-39.
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