<p>Major Histocompatibility Complex (MHC) glycoproteins are heterodimeric cell surface receptors that function to present antigen peptide fragments to T cells responsible for cell-mediated immune responses. MHC molecules can be subdivided into two groups on the basis of structure and function: class I molecules present intracellular antigen peptide fragments (~10 amino acids) on the surface of the host cells to cytotoxic T cells; class II molecules present exogenously derived antigenic peptides (~15 amino acids) to helper T cells. MHC class I and II molecules are assembled and loaded with their peptide ligands via different mechanisms. However, both present peptide fragments rather than entire proteins to T cells, and are required to mount an immune response.</p><p>This entry represents MHC class I and II-like antigen-recognition domains from:</p><ul><li>MHC class II, N-terminal domains of alpha and beta chains [<cite idref="PUB00025626"/>]</li><li>MHC class I, alpha-1 and alpha-2 domains [<cite idref="PUB00035588"/>]</li><li>MHC class I related proteins, such as gammadelta T-cell ligand [<cite idref="PUB00035589"/>], Ulbp3 [<cite idref="PUB00035590"/>], Fc (IgG) receptor (alpha-1 and -2 domains) [<cite idref="PUB00025007"/>], CD1 (alpha-1 and -2 domains) [<cite idref="PUB00035591"/>], zinc-alpha-2-glycoprotein ZAG (fat depleting factor) [<cite idref="PUB00035592"/>]</li><li>Immunomodulatory protein m144, alpha-1 and alpha-2 domains [<cite idref="PUB00035593"/>]</li><li>Haemochromatosis protein Hfe, alpha-1 and alpha-2 domains [<cite idref="PUB00035594"/>]</li><li>NK cell ligand RAE-1 beta [<cite idref="PUB00035595"/>]</li><li>Endothelial protein C receptor (phospholipid-binding protein) [<cite idref="PUB00035596"/>]</li></ul><p>More information about these proteins can be found at Protein of the Month: MHC [<cite idref="PUB00035862"/>].</p> MHC classes I/II-like antigen recognition protein