MHC Class II molecules are heterodimers consisting of two chains: an alpha (α) chain and a beta (β) chain. Both chains are encoded by genes within the MHC locus on chromosome 6 in humans. The α and β chains form a peptide-binding groove that can accommodate peptides of 13-25 amino acids in length. This structure is crucial for the molecule's ability to present a diverse array of peptides to T cells.
