Fig. 7.

Glycosylation in the regulation of receptor endocytosis. Glycosylation on the N-terminus of GPCRs is involved in GPCR localization on the plasma membrane. Studies on dopamine D₃ receptor and PARs suggest that glycosylation on different regions of the receptor is involved in the regulation of different receptor functions. Glycosylation on the N-terminus of D₂R, D₃R, or PAR1 is required for cell-membrane localization. Glycosylation on the N-terminus of D₂R and D₃R mediates their endocytosis within caveolae and CCP microdomains of the plasma membrane, respectively. Glycosylation within the second extracellular loop of D₃R and PAR1 is important for internalization. (Selectivity?) next to PAR1 represents that it is not known whether palmitoylation on the second extracellular loop of PAR1 mediates CME or caveolar endocytosis. GPCR, G protein-coupled receptor; D₃R, dopamine D₃ receptor; D₂R, dopamine D₂ receptor; PAR, protease activator receptor; CCP, clathrin-coated pit.