Control of signalling efficacy by palmitoylation of the rat Y 1 receptor

We have investigated the properties of native and haemagglutinin (HA)‐tagged neuropeptide Y (NPY) Y 1 receptors after mutation of the palmitoylation site Cys 337 to Ser or Ala. In Chinese hamster ovary cells expressing similar receptor levels, the C337A mutation abolished incorporation of [ 3 H]palmitic acid into the HA‐Y 1 receptor. Cys 337 substitution did not alter the affinities of Y 1 receptor agonists or antagonists, but it eliminated the ability of guanosine‐5′‐ O ‐(3‐thio)triphosphate (GTP γ S) to displace [ 125 I]PYY‐specific binding (compared to approximately 50% inhibition in Y 1 or HA‐Y 1 clones). Stimulation of GTP γ [ 35 S] binding by native and HA‐Y 1 receptors in standard incubation buffer (100 m M NaCl, 10 μ M GDP) was prevented by Cys 337 mutation. In this assay, the function of Y 1 (C337S) receptors could be partially rescued by reducing the Na + concentration, and when overexpressed ( B max : ∼10 pmol mg −1 ), both HA‐Y 1 and HA‐Y 1 (C337A) receptors displayed similar responses to NPY and peptide YY (PYY). In stably transfected adenocarcinoma cells expressing Y 1 or Y 1 (C337S) receptors, PYY inhibited anion secretion stimulated by vasoactive intestinal peptide (VIP; measured as short‐circuit current, I SC ) with similar potency (EC 50 : 26–53 n M ). In contrast to the transient Y 1 receptor‐mediated responses observed at maximal PYY concentrations, I SC reductions in both Y 1 (C337S) clones were sustained. We conclude that nonpalmitoylation of the Y 1 receptor reduces its coupling efficiency to G proteins, and may also indirectly influence desensitisation processes that depend on the formation of an active agonist‐receptor conformation.British Journal of Pharmacology (2003) 139 , 501–512. doi: 10.1038/sj.bjp.0705276