Internalization studies of chimeric neuropeptide Y receptors Y1 and Y2 suggest complex interactions between cytoplasmic domains

摘要: Agonist stimulation readily internalizes neuropeptide Y receptor Y1 while there are contradictory results for the Y2 receptor. In order to explore putative functional differences between and receptors we generated reciprocal chimeras by swapping third intracellular loop, carboxy terminus or both human Y2. Internalization was studied in a quantitative radioligand binding assay with removal of surface-bound ligand an acidic-wash procedure. The internalization revealed lower degree as well slower kinetics Generally, exchange segments did not convey properties donor but tended enhance internalization. Surprisingly, insertion into gave almost complete (92%), rather than reduced internalization, resulted equal native These findings were confirmed fluorescence microscopy immuno-stained tagged C-terminal FLAG epitope. However, after exposure high agonist concentrations (100 nM) internalized. Studies closely related Y7 low from chicken teleost fishes two teleosts. conservation across species at physiological suggests that this is ancient feature vital importance function. We propose amino acid motifs loop C able drive agonist-promoted may be constraining