Tyrosinase is an attractive model because of its long in vivo processing time in the endoplastic reticulum (ER). Tyrosinase-derived antigenic peptides are a model system to study human leukocyte antigen (HLA) loading and presentation mechanisms which take place in the ER. This review outlines the results that have been obtained from tyrosinase and some tyrosinase-related proteins which provide insight into the role of ER chaperones in processes related to glycoprotein folding and degradation in vivo.