Requirement of calmodulin-dependent protein kinase II in cyclic ADP-ribose-mediated intracellular Ca2+ mobilization

Shin Takasawa, Atsuhiko Ishida, Koji Nata, Kei Nakagawa, Naoya Noguchi, Akira Tohgo, Ichiro Kato, Hideto Yonekura, Hitoshi Fujisawa, Hiroshi Okamoto

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Cyclic ADP-ribose (cADPR) is generated in pancreatic islets by glucose stimulation, serving as a second messenger for Ca2+ mobilization from the endoplasmic reticulum for insulin secretion (Takasawa, S., Nata, K., Yonekura, H., and Okamoto, H. (1993) Science 259, 370-373). In the present study, we observed that the addition of calmodulin (CaM) to rat islet microsomes sensitized and activated the cADPR-mediated Ca2+ release. Inhibitors for CaM-dependent protein kinase II (CaM kinase II) completely abolished the glucose-induced insulin secretion as well as the cADPR-mediated and CaM-activated Ca2+ mobilization. Western blot analysis revealed that the microsomes contain the α isoform of CaM kinase II but do not contain CaM. When the active 30-kDa chymotryptic fragment of CaM kinase II was added to the microsomes, fully activated cADPR-mediated Ca2+ release was observed in the absence of CaM. These results along with available evidence strongly suggest that CaM kinase II is required to phosphorylate and activate the ryanodine-like receptor, a Ca2+ channel for cADPR as an endogenous activator, for the cADPR-mediated Ca2+ release.

Original languageEnglish
Pages (from-to)30257-30259
Number of pages3
JournalJournal of Biological Chemistry
Issue number51
Publication statusPublished - 1995 Dec 22

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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