MHC class II biosynthetic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the formation of major histocompatibility protein class II. [GOC:go_curators]

MHC class II molecules are crucial for the adaptive immune system, presenting processed antigen peptides to CD4+ T cells, triggering immune responses. The biosynthesis of MHC class II molecules is a complex multi-step process involving various cellular compartments and chaperone proteins. This process begins in the endoplasmic reticulum (ER), where newly synthesized MHC class II alpha and beta chains associate to form heterodimers. These heterodimers bind to the invariant chain (Ii), a chaperone protein that prevents premature association with peptides in the ER and guides them through the secretory pathway. The MHC class II-Ii complex translocates from the ER to the Golgi apparatus, where it undergoes further processing and maturation. The Ii chain is partially degraded by proteases, leaving a small peptide fragment, CLIP (class II-associated invariant chain peptide), bound to the MHC class II molecule. CLIP occupies the peptide-binding groove and prevents premature binding of peptides. In the late Golgi, the MHC class II-CLIP complex encounters another chaperone protein, HLA-DM (human leukocyte antigen-DM). HLA-DM facilitates the exchange of CLIP for antigenic peptides, which are derived from exogenous proteins internalized by antigen-presenting cells (APCs) through endocytosis. This exchange involves the interaction of HLA-DM with the MHC class II molecule, leading to conformational changes and release of CLIP. Once an antigenic peptide is loaded onto the MHC class II molecule, the complex is transported to the cell surface. From there, the MHC class II molecule can present the antigenic peptide to CD4+ T cells, initiating the activation of antigen-specific T cells and triggering the adaptive immune response.'
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Proteins (1)

Compounds (5)