The thin filament of vertebrate skeletal muscle co-operatively activates as a unit

P. W. Brandt, M. S. Diamond, F. H. Schachat

Research output: Contribution to journalLetter

81 Scopus citations

Abstract

We find that extraction of as little as one troponin C molecule per troponin-tropomyosin strand on a thin filament reduces the slope of the pCa/tension relation. We interpret this to mean that the regulatory units along a thin filament of rabbit psoas fibers are linked co-operatively so that a thin filament activates as a unit. The presence of extended co-operativity explains why the pCa/tension relation in skinned fibers has a slope much higher than predicted by binding of Ca2+ to one regulatory unit. Replacement of the extracted troponin C with purified troponin C fully reverses the effect of extraction and shows it to be the essential Ca2+ binding protein responsible for the steep slope of the pCa/tension relation.

Original languageEnglish
Pages (from-to)379-384
Number of pages6
JournalJournal of Molecular Biology
Volume180
Issue number2
DOIs
StatePublished - Dec 5 1984
Externally publishedYes

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