Investigation of immunological relationships among myosin light chains and troponin C

Abstract

Two classes of myosin L chains were distinguished functionally: those that restore Ca regulation to desensitized scallop myofibrils and those that did not. Despite this functional classification, chemical analyses revealed few patterns unique to regulatory L chains, and sequence comparisons suggested structural similarities between both classes of myosin subunits. Immunological assays using antisera to regulatory and to nonregulatory L chains showed no correlation between antigenic activity and the presence or absence of regulatory function. Weak cross-reactivity was observed among myosin L chains and troponin C, consistent with the suggestion made on the basis of sequence homologies that these subunits contain similar structural domains. The strongest cross-reactivity observed was that between the vertebrate myosin alkali 1 and DTNB [5,5''-dithio-bis(2-nitrobenzoic acid)] L chains. [Myosin was prepared from chicken breast muscle. Myosin L chains were from rabbit and lobster muscle.].