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

Abstract 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)3 F(x)3 F in the region of the putative 8th helix has a critical functional relevance for the anterograde transport of hY2 R, 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 hY1 R, hY2 R, hY4 R and hY5 R. Regulation of hY5 R export is regulated by a different mechanism as compared to hY2 R. 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 hY5 R. In contrast to hY2 R, deletion of the corresponding helical segment F(x)3 L(x)3 F has no influence on anterograde transport of hY1 R, whereas deletion of F(x)3 I(x)3 V in hY4 R 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 hY2 R, in hY4 R helix eight is involved at later stages of anterograde transport.