Role and identification of protein kinase A anchoring proteins in vasopressin-mediated aquaporin-2 translocation

The anti-diuretic hormone arginine vasopressin (AVP) regulates water reabso rption in renal principal cells by inducing a cAMP/protein kinase A-depende nt translocation of water channels [aquaporin-2 (AQP2)] from intracellular vesicles into the apical cell membranes. Using primary cultured rat inner m edullary collecting duct (IMCD) cells, it has been shown that AQP2 transloc ation in response to AVP stimulation occurs only if protein kinase A (PKA) is anchored to PKA anchoring proteins (AKAPs). which are present in various subcellular compartments. The identity of the AKAPs involved has not yet b een elucidated. One potential candidate is a new splice variant of AKAP18, namely AKAP18 delta.