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PDBsum entry 4gbx

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Immune system PDB id
4gbx
Jmol
Contents
Protein chains
189 a.a.
191 a.a.
180 a.a.
189 a.a.
Ligands
GLY-LYS-GLN-ASN-
CYS-LEU-LYS-LEU-
ALA-THR
NAG ×3
Waters ×56

References listed in PDB file
Key reference
Title Crystal structure of the hla-Dm-Hla-Dr1 complex defines mechanisms for rapid peptide selection.
Authors W.Pos, D.K.Sethi, M.J.Call, M.S.Schulze, A.K.Anders, J.Pyrdol, K.W.Wucherpfennig.
Ref. Cell, 2012, 151, 1557-1568. [DOI no: 10.1016/j.cell.2012.11.025]
PubMed id 23260142
DOI number 10.1016/J.CELL.2012.11.025
Abstract
HLA-DR molecules bind microbial peptides in an endosomal compartment and present them on the cell surface for CD4 T cell surveillance. HLA-DM plays a critical role in the endosomal peptide selection process. The structure of the HLA-DM-HLA-DR complex shows major rearrangements of the HLA-DR peptide-binding groove. Flipping of a tryptophan away from the HLA-DR1 P1 pocket enables major conformational changes that position hydrophobic HLA-DR residues into the P1 pocket. These conformational changes accelerate peptide dissociation and stabilize the empty HLA-DR peptide-binding groove. Initially, incoming peptides have access to only part of the HLA-DR groove and need to compete with HLA-DR residues for access to the P2 site and the hydrophobic P1 pocket. This energetic barrier creates a rapid and stringent selection process for the highest-affinity binders. Insertion of peptide residues into the P2 and P1 sites reverses the conformational changes, terminating selection through DM dissociation.
PROCHECK
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 Headers