The activation of T lymphocytes usually occurs via the engagement of the aß T-cell receptor (TCR) with major histocompatibility complex (MHC) encoded class I or MHC class II molecules complexed with appropriate peptides which are expressed on antigen presenting cells (APC) . This activation is also significantly influenced by the T-cell coreceptor molecules, CD8 for MHC-I restricted and CD4 for MHC-II restricted cells, as well as other accessory molecules . Each TCR a or ß chain consists of variable and constant immunoglobin(Ig)-like domains, a transmembrane region, and a cytoplasmic tail . The MHC class I molecule is a heterodimer composed of a heavy (α) and α light chain (ß2-microglobulin) with a groove formed by the heavy chain that binds peptides encountered in the endoplasmic reticulum. The heavy chain of this cell surface protein also has a transmembrane and cytoplasmic region, while the non-covalently associated ß2m chain is a single soluble Ig-like domain. The MHC class I molecule presents peptide antigens produced within the APC to the clonally expressed TCR. MHC-I molecules usually bind and present peptides 8–10 amino acids in length [4,5]. In contrast, the a and ß chains of the MHC class II molecule are both intrinsic membrane proteins with transmembrane regions and cytoplasmic tails. The peptide binding groove of the MHC Class II is formed by both the α and ß chains
KeywordsMajor Histocompatibility Complex Surface Plasmon Resonance Major Histocompatibility Complex Class Major Histocompatibility Complex Molecule Peptide Binding Groove
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