The anterograde transport of the human neuropeptide Y2 receptor is regulated by a subtype specific mechanism mediated by the C-terminus

The export of newly synthesized proteins, including G protein-coupled receptors (GPCR), from the endoplasmic reticulum (ER) and further transport to the plasma membrane is a tightly regulated process. ER export and subsequent cell surface targeting of GPCR is initially mediated through COPII-coated vesicles. It is governed by specific amino acid sequences located in extracellular as well as intracellular receptor domains, for example in the C-terminus (CT) of the receptor. Herein, we determined the role of the CT in the anterograde transport of the human neuropeptide Y receptor (hYR) type 2. We identified a short sequence motif in the membrane proximal CT: Y(x)3F(x)3F in the region of the putative 8th helix has a critical functional relevance for the anterograde transport of hY2R, since its deletion leads to accumulation of the receptor in the ER. It is sequence and position specific. Furthermore we identified a distinct role of C-terminal sequences in hY1R, hY2R, hY4R and hY5R. Regulation of hY5R export is regulated by a different mechanism as compared to hY2R. Different sequence elements with respect to function and localization are involved as demonstrated by the construction of a hY2/hY5 receptor chimera and a noneffective deletion in the region of helix eight in the hY5R. In contrast to hY2R, deletion of the corresponding helical segment F(x)3L(x)3F has no influence on anterograde transport of hY1R, whereas deletion of F(x)3I(x)3V in hY4R restrains the receptor to the Golgi apparatus. Interestingly this pattern is not mirrored by repression of COPII vesicle transport by Sar1[H79G] overexpression. Whereas the 8th helix is involved before or at the level of Sar1 dependent export pathways in the ER for the hY2R, in hY4R helix eight is involved at later stages of anterograde transport.