Which poion of MHC1 complex forms the component of antigen presenting pa?: (A) Between alpha 1 and beta 2 microglobulin, (B) Distal pa of alpha chain, (C) Proximal pa of alpha chain, (D) Between alpha 2 and beta 2 microglobulin
Answer is B. Antigen Presenting pa of MHCMHC 1/HLA I:Class 1 molecule consists of three domains of heavy alpha peptide chain (a1; a2; a3) which are non-covalently linked to smaller b2 microglobulin peptide.The distal domain (alpha 1 and alpha 2) of MHC 1 have highly variable amino acid sequences and are folded to form a cavity or groove.Protein antigens are bound to this groove for presentation to CD8 T cells. MHC II/HLA II:MHC II antigens are heterodimer consisting of an alpha and beta chain. Each chain has two domain proximal one is constant and distal one is variable.The two distal domain (alpha 1, beta 1) constitute the antigen binding site, for recognition by CD4 T cells.Both class 1 and class 2 are members of the immunoglobulin gene superfamily.MHC III /HLA III:MHC III are heterogenous they include complement components involved in the formation of C3 convease, heat shock protein and tumor necrosis factor.