HLA-DR antigens-associated invariant chain ; Ia antigen-associated invariant chain ; Ii ; p33 ; CD74 ; DHLAG
Categories
Elisa
Function
Plays a critical role in MHC class II antigen processing by stabilizing peptide-free class II alpha/beta heterodimers in a complex soon after their synthesis and directing transport of the complex from the endoplasmic reticulum to the endosomal/lysosomal system where the antigen processing and binding of antigenic peptides to MHC class II takes place. Serves as cell surface receptor for the cytokine MIF.
Specificity
Natural and recombinant Human HLA class II histocompatibility antigen gamma chain
Subcellular Location
Cell membrane Single-pass type II membrane protein Endoplasmic reticulum membrane Golgi apparatus trans-Golgi network Endosome Lysosome Transits through a number of intracellular compartments in the endocytic pathway. It can either undergo proteolysis or reach the cell membrane.
Homotrimer. In the endoplasmic reticulum (ER) it forms an heterononameric MHC II-Ii complex: 3 MHC class II molecules (heterodimers of an alpha and a beta subunit) bind to the CD74 homotrimer (also known as invariant chain or HLA class II histocompatibility antigen gamma chain). In the endosomal/lysosomal system, the CD74 component undergoes sequential degradation by various proteases, including CTSS and CTSL, leaving a small fragment termed CLIP (class-II-associated invariant chain peptide) attached to the MHC class II molecule (alpha-beta-CLIP complex). This processed complex interacts with HLA_DM and HLA_DO heterodimers in order to release CLIP and facilitate the binding of antigenic peptides to the MHC class II molecules.