Numerous G protein-coupled receptots (GPCRs) are glycosylated at extacellular regions. The regulatory roles of glycosylation on receptor function vary across receptor types. In this study. we used the dopamine D₂ and D₃ receptors as an experimental model to understand the underlying principles governing the functional roles of glycosylation. We used the pharmacological inhibitor. tunicamycin, to inhibit glycosylation. generated chimeric D₂ and D₃ receptors by swapping their respective N-termini. and produced the glycosylation site mutant D₂ and D₃ receptors to study the roles of glycosylation on receptor functions, induding cell surface expression, signaling, and internalization through specific microdomains. Our results demonstrate that glycosylation on the N-terminus of the D₃ receptor is involved in the development of desensitization and proper cell surface expression. In addition, glycosylation on the N-terminus mediates the internalization of D₂ and D₃, receptors within the caveolae and clathrin-coated pit microdomains of the plasma membrane, respectively, by regulating receptor interactions with caveolin-1 and c1athrin. In conclusion, this study shows for the first time that glycosylation on the N-terminus of GPCRs is involved in endocytic pathway selection through specific microdomains. These data suggest that changes in the cellular environment that influence posttranslational modification could be an important determinant of intracellular GPCR trafficking.