HLA class I molecule

Left panel: A ribbon diagram of the classical structure of HLA class I complex of alpha chain and beta-2-microglobulin is presented. The alpha chain is represented in blue and the noncovalently bonded beta-2-microglobulin in red.
Right panel: A schematic representation of the class I complex is shown, which indicates that the peptide binding region is comprised of portions of the alpha-1 and alpha-2 domains of the molecule. The alpha-3 domain is illustrated as being closely associated with beta-2-microglobulin. An extension from the alpha-3 domain penetrates the cell membrane and has a short cytoplasmic region.