Myosin light chain 2 modulates calcium-sensitive cross-bridge transitions in vertebrate skeletal muscle

J. M. Metzger, R. L. Moss

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

We investigated the mechanism of the Ca2+ sensitivity of cross-bridge transitions that limit the rate of force development in vertebrate skeletal muscle. The rate of force development increases with Ca2+ concentration in the physiological range. We show here that at low concentrations of Ca2+ the rate of force development increases after partial extraction of the 20-kD light chain 2 subunit of myosin, whereas reconstitution with light chain 2 fully restores native sensitivity to Ca2+ in skinned single skeletal fibers. Furthermore, elevated free Mg2+ concentration reduces Ca2+ sensitivity, an effect that is reversed by extraction of the light chain but not by disruption of thin-filament activation by partial removal of troponin C, the Ca2+ binding protein of the thin filament. Our findings indicate that the Ca2+ sensitivity of the rate of force development in vertebrate skeletal muscle is mediated in part by the light chain 2 subunit of the myosin cross-bridge.

Original languageEnglish (US)
Pages (from-to)460-468
Number of pages9
JournalBiophysical journal
Volume63
Issue number2
DOIs
StatePublished - 1992
Externally publishedYes

Bibliographical note

Funding Information:
This study was supported by a grant from the National Institutes of Health.

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