Selective effects of CAPP1-calmodulin on its target proteins

Dianne Newton, Claude Klee, James Woodgett, Philip Cohen

    Research output: Contribution to journalArticle

    34 Citations (Scopus)

    Abstract

    Occupancy of one of the two phenothiazine-binding sites on calmodulin does not significantly decrease the affinity of calmodulin for its target proteins; however, it does affect the ability of calmodulin to activate some enzymes. Previously we demonstrated that a covalent adduct of calmodulin with one molecule of phenothiazine (CAPP1-calmodulin) is an antagonist for the calmodulin-dependent enzymes, cAMP phosphodiesterase and myosin kinase, and a partial agonist for calcineurin. We now show that CAPP1-calmodulin is a full agonist for glycogen synthase kinase and phosphorylase kinase. Unlike phenothiazines, CAPP1-calmodulin is specific for calmodulin-regulated proteins; it has no effect on protein kinase C. With the exception of phosphorylase kinase, occupancy of two phenothiazine-binding sites completely eliminates the ability of calmodulin to activate these proteins. Thus, the study of the interaction of CAPP1-calmodulin with calmodulin target proteins demonstrates that calmodulin interacts differently with different proteins. This is confirmed by studies of the effect of calmodulin fragments, 1-77 and 78-148, on calmodulin-regulated enzymes.

    Original languageEnglish
    Pages (from-to)533-539
    Number of pages7
    JournalBBA - Molecular Cell Research
    Volume845
    Issue number3
    DOIs
    Publication statusPublished - 30 Jun 1985

    Keywords

    • Calmodulin
    • Glycogen synthase kinase
    • Phenothiazine binding
    • Phosphorylase kinase

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