Regulation of the 63-kDa Subunit-Containing Calmodulin-Dependent Cyclic Nucleotide Phosphodiesterase Isozyme
Calmodulin-stimulated cyclic nucleotide phosphodiesterase, originally thought to be a single enzyme species in all tissues has been shown to exist in isozymic forms [for review, 1–5]. Homogeneous preparations of calmodulin-dependent phosphodiesterases showing distinct kinetic, regulatory, molecular and immunological properties have been obtained [for review, see (1)]. The well-characterized mammalian isozymes possess low basal (Ca2+-independent) activity and exhibit relatively low affinity towards cyclic AMP. Thus, it appears that these enzymes function most efficiently when cells are stimulated to increase the concentration of both Ca2+ and cAMP and, as such, they are expected to play important roles in integrating the regulatory actions of Ca2+ and cAMP.
KeywordsDependent Protein Kinase Cyclic Nucleotide Phosphodiesterase Phosphate Incorporation Calmodulin Action Phosphodiesterase Isozyme
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