Required for endocytosis and endosomal pH regulation. Associated with the endosome/lysosome system. Present at low levels in vegetative cells, peaks at roughly 5 hours and decrease by 10 hours. There is another peak of production at 12.5 hours, and a slight increase beginning at 20 hours (at protein level). Cells that have a abcG2-abcG18 disruption have an endocytosis rate roughly 70% that of wild-type (or rtoA disrupted cells). Disruption on abcG2-abcG18-rtoA cells have an endocytosis rate roughly 20% that of wild-type. The exocytosis rates of abcG2-abcG18 and abcG2-abcG18-rtoA disrupted cells are roughly that of wild-type; abcG2-abcG18 endosomes have an unusually high pH, whereas abcG2-abcG18-rtoA endosomes have an almost normal pH. Belongs to the ABC transporter superfamily. ABCG family. PDR (TC 3.A.1.205) subfamily.