Renal V2 vasopressin receptor proteins: identification and enrichment

The synthesis of the tritium labelled photoreactive analogue of 1-deamino-vasopressin [1-(3-mercaptopropionic acid, 8-(N6-4-azido-phenylamidino)-lysine] vasopressin is described. This analogue retains a high affinity for hepatic V1 and renal V2 vasopressin receptors (apparent dissociation constant KD approximately 1-2 nM). A membrane protein from bovine kidney and pig kidney with an apparent relative molecular mass (Mr) of 30,000 was preferentially labelled and with lower yield a protein band with a Mr-value of 50,000 to 60,000. The photolabelled 30,000-Mr protein from bovine kidney was enriched by size-exclusion chromatography and by reversed-phase-high-performance liquid chromatography.