Figure 11. In vitro bioactivity of different V2-R constructs relative to wild type (WT) in a cAMP-dependent luciferase reporter system in the absence of AVP. The R137H construct is the V2-R found in X-linked NDI. R137C and R137L are receptor variants found in NSIAD. Constructs differ only by the amino acid at position 137. R137C and R137L found in NSIAD demonstrate constitutive, AVP-independent activity. R: arginine. H: histidine. C: cysteine. L: leucine.