Elsevier

Biophysical Chemistry

Volume 59, Issue 3, 16 April 1996, Pages 357-363
Biophysical Chemistry

Regulation of contraction by calcium binding myosins

https://doi.org/10.1016/0301-4622(95)00128-XGet rights and content

Abstract

Contraction of molluscan muscles is triggered by binding of Ca2+ to myosin. Molluscan myosins are regulated molecules, their light chains serve as regulatory subunits. They differ from myosins of skeletal muscles in requiring Ca2+ for activity and having a specific high-affinity Ca2+ binding site. As all conventional myosins molluscan myosins also consist of two heavy chains, two regulatory and two essential light chains. Scallop myosin is particularly suitable for studying light chain function since its regulatory light chains readily dissociate in the absence of divalent cations and its essential light chains can be exchanged with foreign light chains. The structural, mutational and biochemical studies presented here are aimed to elucidate the role of the light chains in regulation, to describe the interactions between the myosin subunits and to locate the regions and the amino acids responsible for the differences between functional and non-functional light chains.

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      Regulation of molluscan muscle myosins is controlled by direct binding of Ca2+ to the essential light chain (ELC) (2). Calcium binding to the ELC mediates the communication between the ELC and the regulatory light chain (RLC), such that regulation in molluscan myosin requires both light chains (3). To investigate regulation in molluscan myosin, our laboratory previously determined the crystal structures of Ca2+-bound and Ca2+-free scallop striated muscle light chain domains (LCDs) (4,5).

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