These are glycoproteins found on the surface of antigen presenting cells like macrophages, B cells, dendritic cells of the spleen and Langerhans cells of the skin. MHC class II proteins are coded by HLA-D loci on the chromosome 6. These proteins interact with CD4 carrying T-helper cells.
Look at the figure first
|Class II MHC Proteins Structure|
Similar to immunoglobulin, α chain and β chain has 4 regions, constant C terminal regions and hyper variable N-terminal regions comprising of a
a) Cytoplasmic carboxyl region for phosphorylation and cytoskeletal binding
b) A transmembrane region composed of hydrophobic amino acids providing anchorage.
c) A highly conserved α-2 and β-2 domain
d) A highly polymorphic or hypervariable peptide binding N terminal region made of α-1 and β -1 regions.
Functions of MHC class II proteins
- Helps immune system in recognising self-cells from non-self cells.
- Helper T cells recognises antigens bound to MHC Class II proteins