The topology of the Or83b protein. (A) Predicted topology of OR83b. Phobius [8] predicts an Nin-Cout topology with the following seven transmembrane helices: 50–68, 80–98, 137–158, 194–213, 350–371, 391–413, 462–483. Engineered and endogenous (N33FT, N169SS and N188AS encircled) putative glycosylation sites are indicated; sites that become modified upon insertion into DRMs are in black, non-modified sites are in gray. (B) Glycosylation mapping of OR83b. In vitro translation of OR83b wild type and variants with engineered glycosylation sites in the absence (-DRM) and presence (+DRM) of Drosophila rough microsomes. Molecules glycosylated only on the endogenous N169SS site are indicated by * and molecules glycosylated on an additional engineered site are indicated by arrows.