Involved in the presentation of foreign antigens to the immune system. Heterodimer of an alpha chain and a beta chain (beta-2-microglobulin). Polyubiquitinated in case of infection by murid herpesvirus 4, by the viral E3 ligase K3 (mK3), leading to target the protein for rapid degradation by the endoplasmic reticulum-associated degradation (ERAD) system. Ubiquitination takes place on lysine, as well as serine and threonine residues present in the cytoplasmic tail. Hydroxylated serine and threonine residues in the cytoplasmic tail are subject to ubiquitination via ester bonds instead of the classical isopeptide linkage (Probable). Hydroxylation of residues in the cytoplasmic tail. Belongs to the MHC class I family.