Cyclic AMP-dependent phosphodiesterase type D (PDE4D) family is comprise of 5 variants (PDE4D1, D2, D3, D4 and D5, 1, 2). One or more PDE4D subtype-variants are ubiquitously present in all mammalian cells. In CNS all five PDE4D subtype-variants are expressed in varying ratios and their activity is regulated in tandem with GPCRs stimulation. Peripheral tissues also exhibit differential expression of PDE4D variants. PDE4D1/D2 mRNA levels rise in response to an increase in cAMP. Short-term regulation of PDE4D variants involved PKA, MAP kinases and Erk2 phosphorylation that results in rapid change in their enzymatic activities. Other regulatory mechanism involved protein-protein interactions with cytoskeletal scaffolding proteins. Description: Recombinant human PDE4D3 (GenBank Accession No. NM_006203, full length, with N-terminal GST tag, expressed in an Baculovirus infected Sf9 cell expression system. Specific Activity: ~5000pmol/min/ug Assay Conditions: 10mM Tris-HCl, pH 7.4, 10mM MgCl2, 1mM MnCl2, 200uM cAMP, 0.1mg/ml BSA, 0.2ng/ul P4072-03W at 37C for 20 minutes. Application: Useful for the study of enzyme kinetics, screening inhibitors, and selectivity profiling. Other applications not tested. Recommended Dilutions: Optimal dilutions to be determined by the researcher. Storage and Stability: Aliquot to avoid repeated freezing and thawing and store at -70C. Aliquots are stable for 6 months. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.