HLA-DR Antibody – Mouse

The protein encoded by this gene associates with class II major histocompatibility complex (MHC) and is an important chaperone that regulates antigen presentation for immune response. It also serves as cell surface receptor for the cytokine macrophage migration inhibitory factor (MIF) which, when bound to the encoded protein, initiates survival pathways and cell proliferation. This protein also interacts with amyloid precursor protein (APP) and suppresses the production of amyloid beta (Abeta). Multiple alternatively spliced transcript variants encoding different isoforms have been identified. [provided by RefSeq, Aug 2011]

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.

Subunit structure: Homotrimer. In the endoplasmic reticulum (ER) it forms a 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. Ref.13

Subcellular location: Cell membrane; Single-pass type II membrane protein

Potential. Endoplasmic reticulum membrane. Golgi apparatus › trans-Golgi network. Endosome. Lysosome. Note: Transits through a number of intracellular compartments in the endocytic pathway. It can either undergo proteolysis or reach the cell membrane.

Post-translational modification: N- and O-glycosylated. O-glycosylated with core 1 or possibly core 8 glycans. Ref.17 Ref.18 Ref.21

Involvement in disease: A chromosomal aberration involving CD74 is found in a non-small cell lung tumor. Results in the formation of a CD74-ROS1 chimeric protein. Ref.12

Sequence similarities: Contains 1 thyroglobulin type-1 domain.

Sequence caution: The sequence AAA36304.1 differs from that shown. Reason: Erroneous initiation.