Biochemical and functional characterization of the synaptic vesicle-associated form of Ca2+/calmodulin-dependent protein kinase II

Fabio Benfenati, Franco Onofri, Andrew J. Czernik, Flavia Valtorta

Research output: Contribution to journalArticle


Ca2+/calmodulin-dependent protein kinase-II (CaMPKII) is a brain-enriched protein kinase that plays important roles in synaptic transmission and plasticity, In nerve terminals, a form of CaMPKII is associated with synaptic vesicles and binds the COOH-terminal region of synapsin I (SYNI). The biochemical properties of the vesicle-associated form of CaMPKII have been investigated and compared with those of the soluble forebrain enzyme. Both the α- and β-subunits of CaMPKII copurifying with synaptic vesicles were tightly associated with the vesicle membrane. The vesicle-associated form of CaMPKII was indistinguishable from the soluble form with respect to sites of autophosphorylation, kinetics of both autophosphorylation and SYNI phosphorylation, and induction of autonomous activity upon autophosphorylation. Although both subunits of the soluble CaMPKII interacted with a photoactivatable SYNI derivative, only the a-subunit of the synaptic vesicle-associated CaMPKII bound to the COOH-terminal region of SYNI. The latter interaction was strongly dependent on the phosphorylation state of SYNI and on divalent cations, but appeared to be independent of autophosphorylation. These results demonstrate that, although the vesicle-associated form of CaMPKII is catalytically indistinguishable from the soluble form, it exhibits distinct characteristics concerning its association with the vesicle membrane and with SYNI.

Original languageEnglish
Pages (from-to)297-309
Number of pages13
JournalMolecular Brain Research
Issue number2
Publication statusPublished - Sep 1 1996



  • CaM kinase II
  • Neurotransmitter release
  • Synapsin I
  • Synaptic vesicles

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience

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