Insulin control of cyclic AMP phosphodiesterase.

Cyclic AMP phosphodiesterase (PDE) is an enzyme involved in cellular homeostasis of cyclic AMP. It exists as multiple isozymes in cells, but only the high affinity, membrane-bound isozyme is sensitive to hormonal modulation. Several isozymes or isoforms of the low Km PDE have been detected. Data suggest that several mechanisms exist for hormonal modulation of PDE. Activity of the low Km PDE species may be modulated by phosphorylation/dephosphorylation, phospholipid substrate concentration, insulin second messenger, cyclic GMP, guanine nucleotide binding proteins, calmodulin, or aggregation/disaggregation of monomeric forms. Modulation of PDE isoforms by different hormones may be through different regulatory components or mechanisms.