Molecular Cloning of the cDNA Encoding β-Cell Calcium/Calmodulin-Dependent Protein Kinase II
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Current hypotheses postulate that the metabolism of glucose within islets results in a transient increase in the ATP:ADP ratio, leading to depolarization and opening of voltage-dependent Ca2+ channels, promoting influx of Ca2+ into the β-cell. The increase in intracellular calcium may activate Ca2+-dependent protein kinases, which in turn phosphorylate key components in the secretory machinery. The nature and identity of these components are at present unclear. In addition, the β-cell contains a high (15–50 μM) concentration of calmodulin (CaM) and it has been shown that inhibitors of CaM block insulin secretion. Possible candidates for Ca2+/calmodulin-dependent protein kinases acting as regulatory enzymes in the exocytotic release process are phosphorylase kinase, myosin light chain kinase and CaM kinases.
KeywordsNorthern Analysis Myosin Light Chain Kinase Phosphorylase Kinase Autographa Californica Nuclear Polyhedrosis Virus Encode Protein Kinase
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