Ultracentrifugation study on interactions among calmodulin, cardiac troponin and tropomyosin-actin complex

Kazuhiko Yamamoto, Kiyohide Nunoi, Masatoshi Fujishima

    Research output: Contribution to journalArticlepeer-review

    1 Citation (Scopus)

    Abstract

    In an effort to clarify the regulation of contractions in cardiac muscle, we performed ultracentrifugation studies on the interactions between cardiac troponin and tropomyosin-actin complex in the presence of Ca2+ or Sr2+. When troponin C and troponin I were centrifuged with tropomyosin-actin complex, troponin I was not removed from tropomyosin-actin complex in the presence of bivalent-cation. Troponin C was observed to bind very weakly to troponin T-tropomyosin-actin complex in either the presence or absence of bivalent-cation. When troponin C was replaced by calmodulin, troponin I was not removed from tropomyosin-actin complex in the presence of bivalent-cation. Calmodulin bound to the troponin I-troponin T-tropomyosin-actin complex only in the presence of bivalent-cation. These results suggest that the inhibitory action of troponin I is neutralized by troponin C or calmodulin upon binding of bivalent-cation while troponin I binds to tropomyosin-actin complex in cardiac muscle. Therefore cardiac muscle seems to differ from skeletal muscle in regard to regulation of its contraction.

    Original languageEnglish
    Pages (from-to)279-285
    Number of pages7
    JournalJournal of Molecular and Cellular Cardiology
    Volume22
    Issue number3
    DOIs
    Publication statusPublished - Mar 1990

    All Science Journal Classification (ASJC) codes

    • Molecular Biology
    • Cardiology and Cardiovascular Medicine

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