Regulation of Ca2+/calmodulin-dependent protein kinase II by inter- and intrasubunit-catalyzed autophosphorylations

S. Mukherji, T. R. Soderling

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    106 Scopus citations

    Abstract

    Autophosphorylation of CaM kinase II on Thr286 is known to occur by an intraholoenzyme mechanism, but it is not known whether this reaction is intra- or intersubunit-catalyzed in the native heteromeric enzyme containing 10-12 α/β subunits. In this study inactive CaM kinase II β subunit, generated by mutation of Lys43 to Ala, and active kinase α subunit were expressed separately (homomeric kinases) or co-expressed (heteromeric kinase) using the baculovirus/Sf9 cell expression system and purified on CaM- Sepharose. Ca2+/CaM-dependent autophosphorylation of heteromeric α/β kinase, which activated the enzyme, produced rapid autophosphorylation on Thr286 in both the active α and inactive β subunits; the latter could only occur by intersubunit catalysis. Ca2+/CaM-independent autophosphorylation of nonactivated heteromeric kinase was slow, resulted in partial loss of total kinase activity, occurred only in the α subunit, and existed on Thr306 but not Thr286. This result demonstrates intrasubunit catalysis of Thr306 autophosphorylation. These observations that regulatory autophosphorylations of Thr286 and Thr306 were inter- and intrasubunit-catalyzed, respectively, have important consequences for structure/function models of CaM kinase II and for involvement of CaM kinase II autophosphorylation and activation during synaptic plasticity in neural systems.

    Original languageEnglish (US)
    Pages (from-to)13744-13747
    Number of pages4
    JournalJournal of Biological Chemistry
    Volume269
    Issue number19
    StatePublished - 1994

    ASJC Scopus subject areas

    • Biochemistry
    • Molecular Biology
    • Cell Biology

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