Similar to the human SNP, the A112G variant in the mouse alters Asn to Asp at position 38 (N38D) of the mouse MOPR [18], eliminating a potential N-linked glycosylation site accordingly (Fig. 1). We have observed significant reductions of MOPR protein levels in the thalamus and whole brain of G/G mice, compared with A/A mice [18]. In the present studies, we investigated whether the SNP affected N-glycosylation of MOPR by comparing the G112/D38-MOPR in G/G mice with A112/N38-MOPR in A/A mice using immunoblotting combined with deglycosylation experiments. Similar experiments were conducted on the two hMOPR variants (A118/N40-hMOPR and G118/D40-hMOPR) stably expressed in CHO cells. In addition, pulse-chase experiments were performed with those cell lines to determine the half-lives of A118/N40-hMOPR and G118/D40-hMOPR.
