Adenylate Cyclase 2

T

he membrane-bound adenylyl cyclases (ACs) represent one of the major families of effector enzymes for G protein-coupled receptors (GPCRs).  Using the high inter-species homology of mammalian AC isoforms, nine Adenylyl cyclase (AC) isoforms, encoded by separate genes, have been identified until today.  Human adenylate cyclase genes comprise of 11 to 26 exons, which are distributed over 16 to 430kb.  The expression profile of these 9 AC isoforms in a panel of 16 human tissues and in human embryonic kidney (HEK) cells have been demonstrated earlier (1).  The cAMP synthesizing enzymes are found in two forms: cytosolic (soluble) and membrane-bound (particulate).  Stimulation of adenylate cyclases produce cAMP form ATP in response to the activation of GPCRs by various hormones, neurotransmitters and other regulatory molecules.  cAMP, in subsequent steps down the signal transduction pathway, can stimulate cAMP-dependent protein kinase A (cPKA), and several other target molecules.  Activation of cPKA can phosphorylate a broad range of substrates that regulate various metabolic pathways, gene expression, and affect memory functions etc., (3, 4).  The stimulation of adenylate cyclases starts with interactions with GPCRs mediated signals initiated by Gs and Gi heterotrimeric G-proteins.  The interaction of GPCR agonist (eg. Interaction of isopreternol to beta2 receptors) catalyses the exchange of GDP to GTP that is bound to G proteins.  The GTP binding reduces the affinity of Gsa to other  GTP binding proteins and Gs-GTP complex stimulate the adenylate cyclase (5).  In last several years, new members of particulate and soluble adenylate cyclase family have been identified and significant progress is made in understanding of the molecular mechanisms that underlie the regulation of these families of enzymes. 

For research use only, not for diagnostic or therapeutic use.