Myosin-Linked Regulatory Systems: The Role of the Light Chains
This extract was created in the absence of an abstract.
Excerpt
Muscular contraction is regulated by the interaction of calcium with the contractile elements. In vertebrate muscles the specific regulatory proteins, tropomyosin, and the troponin complex (Ebashi and Kodama, 1965, 1966) are associated with the thin filaments (Ohtsuki et al., 1967). Tropomyosin is required for relaxation, its role being to mediate the changes on troponin which affect the active sites of actin (Ebashi and Endo, 1968; Weber and Bremel, 1971). In molluscan muscles calcium regulation is associated with myosin; troponin and its components are absent, and tropomyosin, although present on the thin filaments, is not required for regulation. Purified molluscan myosin preparations bind calcium, and their ATPase activity depends on calcium when combined with pure actin (Kendrick-Jones et al., 1970).
In this paper we define those components of the myosin preparations which are responsible for calcium regulation. The removal of a particular light chain from myosin with EDTA leads to a...
