Structural characterization of the TCR complex by electron microscopy.
Structural information on how the TCR transmits signals upon binding of its antigen peptide MHC molecule ligand is still lacking. The ectodomains of the TCRα/β, CD3εγ and CD3εδ dimers, as well as the transmembrane domain of CD3ζ, have been characterized by X-ray crystallography and nuclear magnetic resonance (NMR). However, no structural data have been obtained for the entire TCR complex. In this study, we have purified the TCR from T cells under native conditions and used electron microscopy to derive a three-dimensional structure. The TCR complex appears as a pear-shaped structure of 180 × 120 × 65 . Furthermore, the use of mAbs has allowed to determine the orientation of the TCRα/β and CD3 subunits and to suggest a model of interactions. Interestingly, the reconstructed TCR is larger than expected for a complex with a αβγεδεζζ stoichiometry. The accommodation of a second TCRαβ to fill in the extra volume is discussed.
Departamento de Biología Molecular, Universidad de Cantabria (UC) and Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC (CSIC-UC-IDICAN), c/Herrera Oria s/n, 39011 Santander, Spain.
Ignacio
I
Arechaga
Mahima
M
Swamy
David
D
Abia
Wolfgang A
WA
Schamel
Balbino
B
Alarcón
José María
JM
Valpuesta
D000818:Animals; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008854:Microscopy, Electron; D008958:Models, Molecular; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry* / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000737:chemistry / Q000276:immunology
D011948:Receptors, Antigen, T-Cell