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. 1992 Aug;63(2):460–468. doi: 10.1016/S0006-3495(92)81614-4

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

J M Metzger 1, R L Moss 1
PMCID: PMC1262169  PMID: 1420891

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.

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Selected References

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