CD74 Recombinant Mouse Monoclonal Antibody [PDM0-22] (HA601117)

UNIPROT #

P04233

PROTEIN NAME

CD74

SYNONYMS

CD 74 antibody;CD74 antibody;CD74 antigen (invariant polypeptide of major histocompatibility complex, class II antigen-associated) antibody;CD74 antigen antibody;CD74 molecule antibody;CD74 molecule, major histocompatibility complex, class II invariant chain antibody;CLIP antibody;DHLAG antibody;Gamma chain of class II antigens antibody;HG2A_HUMAN antibody;HLA class II histocompatibility antigen gamma chain antibody;HLA DR antigens associated invariant chain antibody;HLA DR gamma antibody;HLA-DR antigens-associated invariant chain antibody;HLA-DR-gamma antibody;HLADG antibody;HLADR antigens associated invariant chain antibody;Ia antigen associated invariant chain antibody;Ia antigen-associated invariant chain antibody;Ia associated invariant chain antibody;Ia gamma antibody;Ii antibody;Invariant polypeptide of major histocompatibility complex class II antigen associated antibody;la-gamma antibody;Major histocompatibility complex class II invariant chain antibody;MHC HLA DR gamma chain antibody;MHC HLA-DR gamma chain antibody;p33 antibody;p35 antibody;Protein 41 antibody

SUBCELLULAR LOCATION

Endoplasmic reticulum membrane, trans-Golgi network, cell membrane, lysosome, endosome.

FUNCTION

HLA class II histocompatibility antigen gamma chain also known as HLA-DR antigens-associated invariant chain or CD74 (Cluster of Differentiation 74), is a protein that in humans is encoded by the CD74 gene. The invariant chain (Abbreviated Ii) is a polypeptide which plays a critical role in antigen presentation. It is involved in the formation and transport of MHC class II peptide complexes for the generation of CD4+ T cell responses. The cell surface form of the invariant chain is known as CD74. CD74 is a cell surface receptor for the cytokine macrophage migration inhibitory factor (MIF). The nascent MHC class II protein in the rough endoplasmic reticulum (RER) binds a segment of the invariant chain (Ii; a trimer) in order to shape the peptide-binding groove and prevent the formation of a closed conformation. The invariant chain also facilitates the export of MHC class II from the RER in a vesicle. The signal for endosomal targeting resides in the cytoplasmic tail of the invariant chain. This fuses with a late endosome containing the endocytosed antigen proteins (from the exogenous pathway). Binding to Ii ensures that no antigen peptides from the endogenous pathway meant for MHC class I molecules accidentally bind to the groove of MHC class II molecules. The Ii is then cleaved by cathepsin S (cathepsin L in cortical thymic epithelial cells), leaving only a small fragment called CLIP remaining bound to the groove of MHC class II molecules. The rest of the Ii is degraded. CLIP blocks peptide-binding until HLA-DM interacts with MHC II, releasing CLIP and allowing other peptides to bind. In some cases, CLIP dissociates without any further molecular interactions, but in other cases the binding to the MHC is more stable. The stable MHC class II + antigen complex is then presented on the cell surface. Without CLIP, MHC class II aggregates disassemble and/or denature in the endosomes, and proper antigen presentation is impaired.