Regulation of the activities of multifunctional Ca2+/calmodulin-dependent protein kinases |
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Authors: | Fujisawa H |
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Institution: | Department of Biochemistry, Asahikawa Medical College, Asahikawa, Hokkaido 078-8510, Japan. fujisawa@asahikawa-med.ac.jp |
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Abstract: | Ca2+/calmodulin-dependent protein kinases (CaM-kinases) II, IV, and I play important roles as Ca2+ responsive multifunctional protein kinases in controlling a variety of cellular functions in response to an increase in intracellular Ca2+, and hence regulation of their activities is very important. CaM-kinase II is activated through autophosphorylation of threonine-286 (in the case of alpha isoform), and CaM-kinases IV and I are activated through phosphorylation of threonine-196 and 177, respectively, by CaM-kinase kinase. After activation, CaM-kinases II and IV lose their Ca2+/calmodulin-dependent activity upon autophosphorylation of threonine-305 and serine-332, respectively, in the absence of Ca2+, becoming Ca2+/calmodulin-independent forms. The activated CaM-kinases II, IV, and I are deactivated upon dephosphorylation of phosphothreonine-286, 196, and 177, respectively, by CaM-kinase phosphatase or other multifunctional protein phosphatases and restored to the original ground states. Thus, the activities of the three multifunctional CaM-kinases are regulated by phosphorylation and dephosphorylation. |
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