American journal of physiology. Renal physiology
-
Am. J. Physiol. Renal Physiol. · Jan 2000
Localization and regulation of PKA-phosphorylated AQP2 in response to V(2)-receptor agonist/antagonist treatment.
Phosphorylation of Ser(256), in a PKA consensus site, in AQP2 (p-AQP2) appears to be critically involved in the vasopressin-induced trafficking of AQP2. In the present study, affinity-purified antibodies that selectively recognize AQP2 phosphorylated at Ser(256) were developed. These antibodies were used to determine 1) the subcellular localization of p-AQP2 in rat kidney and 2) changes in distribution and/or levels of p-AQP2 in response to [desamino-Cys(1),D-Arg(8)]vasopressin (DDAVP) treatment or V(2)-receptor blockade. ⋯ The overall abundance of p-AQP2, however, was not increased, as determined both by immunoelectron microscopy and immunoblotting. Consistent with this, 2 h of DDAVP treatment of normal rats also resulted in unchanged p-AQP2 levels. Thus the results demonstrate that AQP2 phosphorylated in Ser(256) is present in the apical plasma membrane and in intracellular vesicles and that both the intracellular distribution/trafficking, as well as the abundance of p-AQP2, are regulated via V(2) receptors by altering phosphorylation and/or dephosphorylation of Ser(256) in AQP2.