MHC-I/I类分子抗原结合区的区别 TABLE 7-2 PEPTIDE BINDING BY CLASS I AND CLASS II MHC MOLECULES Class I molecules Class II molecules Peptide-binding domain a1/x2 a1/B1 Nature of peptide-binding cleft Closed at both ends Open at both ends General size of bound peptides 8-10 amino acids 13-18 amino acids Peptide motifs involved in Anchor residues at both ends of Anchor residues distributed binding to MHC molecule peptide:generally hydrophobic along the length of the peptide carboxyl-terminal anchor Nature of bound peptide Extended structure in which both ends Extended structure that is held interact with MHC cleft but middle at a constant elevation above the arches up away from MHC molecule floor of MHC cleft MHC-Ⅰ/Ⅱ类分子抗原结合区的区别