title: Self-release of CLIP in peptide loading of HLA-DR molecules.
abstract: The assembly and transport of major histocompatibility complex (MHC) class II molecules require interaction with the invariant chain. A fragment of the invariant chain, CLIP, occupies the peptide-binding groove of the class II molecule. At endosomal pH, the binding of CLIP to human MHC class II HLA-DR molecules was counteracted by its amino-terminal segment (residues 81 to 89), which facilitated rapid release. The CLIP (81-89) fragment also catalyzed the release of CLIP(90-105) and a subset of other self-peptides, probably by transient interaction with an effector site outside the groove. Thus, CLIP may facilitate peptide loading through an allosteric release mechanism.
mesh_terms: D000595:Amino Acid Sequence; D000944:Antigens, Differentiation, B-Lymphocyte / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D002460:Cell Line; D015803:HLA-DR3 Antigen / Q000378:metabolism*; D000949:Histocompatibility Antigens Class II / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008239:Lysine / Q000737:chemistry; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D011392:Proline / Q000737:chemistry; D011487:Protein Conformation
chemical_list: D000944:Antigens, Differentiation, B-Lymphocyte; D015803:HLA-DR3 Antigen; D000949:Histocompatibility Antigens Class II; D010446:Peptide Fragments; C045084:invariant chain; D011392:Proline; D008239:Lysine