期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2004
卷号：101
期号：46
页码：16268-16273
DOI：10.1073/pnas.0407359101
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：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.
