1xiw
From Proteopedia
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Crystal structure of human CD3-e/d dimer in complex with a UCHT1 single-chain antibody fragment
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Overview
The alpha/beta T cell receptor complex transmits signals from MHC/peptide antigens through a set of constitutively associated signaling molecules, including CD3-epsilon/gamma and CD3-epsilon/delta. We report the crystal structure at 1.9-A resolution of a complex between a human CD3-epsilon/delta ectodomain heterodimer and a single-chain fragment of the UCHT1 antibody. CD3-epsilon/delta and CD3-epsilon/gamma share a conserved interface between the Ig-fold ectodomains, with parallel packing of the two G strands. CD3-delta has a more electronegative surface and a more compact Ig fold than CD3-gamma; thus, the two CD3 heterodimers have distinctly different molecular surfaces. The UCHT1 antibody binds near an acidic region of CD3-epsilon opposite the dimer interface, occluding this region from direct interaction with the TCR. This immunodominant epitope may be a uniquely accessible surface in the TCR/CD3 complex, because there is overlap between the binding site of the UCHT1 and OKT3 antibodies. Determination of the CD3-epsilon/delta structure completes the set of TCR/CD3 globular ectodomains and contributes information about exposed CD3 surfaces.
Disease
Known diseases associated with this structure: Immunodeficiency due to defect in CD3-epsilon OMIM:[186830], Severe combined immunodeficiency, T-negative/B-positive type OMIM:[186790]
About this Structure
1XIW is a Protein complex structure of sequences from Homo sapiens and Mus musculus. Full crystallographic information is available from OCA.
Reference
Crystal structure of a human CD3-epsilon/delta dimer in complex with a UCHT1 single-chain antibody fragment., Arnett KL, Harrison SC, Wiley DC, Proc Natl Acad Sci U S A. 2004 Nov 16;101(46):16268-73. Epub 2004 Nov 8. PMID:15534202
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