This mini-review addresses the effect of glycosylation and phosphorylation on the conformational alterations of the epidermal growth factor receptor (EGFR). Based on studies with full-length and truncated EGFRs, we propose a model to suggest that receptor–receptor self-association, which occurs in the truncated receptor and depends on core glycosylation, is prevented in intact receptor by a certain extracellular domain and that the function of the ligand is to remove the negative constraint. We also propose, based on works with a conformation-specific antibody directed to an unphosphorylated peptide, that the interactions among negatively charged phosphotyrosine residues in the receptor molecule result in bringing two epitopes separated by a long stretch of amino acids close to each other to form an antibody-binding site. The implications of these posttranslational modifications on receptor functions are also discussed in this article.