The structure and function of the vasopressin V₁a receptor

• Main Author: Logan, Richard Thomas
• Published: University of Birmingham 2013
• Subjects: 500; QH301 Biology
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.567786

The neurohypophysial hormone [arginine⁸]vasopressin (AVP) exerts the majority of its physiological roles through the G-protein-coupled receptor, V₁a R. AVP binding to the V₁a R promotes receptor activation and generates signalling though the inositol phosphate pathway. ICL 2 has been implicated in many aspects of GPCR signalling and crystallographic data highlight the structurally dynamic nature of this region. A complete alanine-scanning study of ICL 2 has not previously been conducted in a GPCR but is presented here in the prototypical peptide-ligand GPCR, V₁a R. However, a role of Leu³.⁵⁸ in mediating G-protein-dependent signalling was observed in the V₁a R – a finding that has previously been reported in other GPCRs. Upon agonist binding, the structural rearrangements of TM V and TM VI are integral in signal transduction in GPCRs. Two highly conserved residues, Tyr⁵.⁵⁸ and Ile⁶.⁴⁰ are key players in the activation process. Given their high conservation, it was presumed that their roles are universal throughout the rhodopsin-like GPCR family. The systematic substitution of these two residues in the V₁a R demonstrate the receptor-specific nature of substitutions of Tyr⁵.⁵⁸ and Ile⁶.⁴⁰ given that findings in the V₁a R are not recapitulated in the generally limited mutagenic studies in other receptors.