Major histocompatibility complex

Function

Major Histocompatibility Complex (MHC) molecules bind peptides derived from degraded proteins and present these peptides on the surface of the cell. T-cells or natural killer receptors recognize the MHC:peptide complex and trigger an immune response if the presented peptide (“antigen”) is suggestive of a pathogenic or foreign protein. Thus, MHC molecules allow for immune system detection of intracellular activity, making them an essential part of the organism’s immune system.

• MHC class I (Major Histocompatibility Complex Class I) are found in all nucleated cells. These cell surface proteins display peptides from cellular intrinsic proteins^[1]. For more details see
  
• Effect of HCMV on Major Histocompatibility Complex Class I
  
• MR1 Binds Vitamin Metabolites.
  
• MHC class II are found in professional antigen-presenting cells like macrophages. These cell surface proteins display peptides from cellular extrinsic proteins^[2].
  

For MHC class II interactions with T-cell receptor and gliadin peptide see SP3.4-TCR-HLA-DQ8-α-1-gliadin complex.

Structural highlights

. The ^[3]. Water molecules shown as red spheres.

3D structures of MHC

MHC 3D structures of MHC