2HAC: Structure of Zeta-Zeta Transmembrane Dimer

The T cell receptor (TCR) alphabeta heterodimer communicates ligand binding to the cell interior via noncovalently associated CD3gammaepsilon, CD3deltaepsilon, and zetazeta dimers. While structures of extracellular components of the TCR-CD3 complex are known, the transmembrane (TM) domains that mediate assembly have eluded structural characterization. Incorporation of the zetazeta signaling module is known to require one basic TCRalpha and two zetazeta aspartic acid TM residues. We report the NMR structure of the zetazeta(TM) dimer, a left-handed coiled coil with substantial polar contacts. Mutagenesis experiments demonstrate that three polar positions are critical for zetazeta dimerization and assembly with TCR. The two aspartic acids create a single structural unit at the zetazeta interface stabilized by extensive hydrogen bonding, and there is evidence for a structural water molecule (or molecules) within close proximity. This structural unit, representing only the second transmembrane dimer interface solved to date, serves as a paradigm for the assembly of all modules involved in TCR signaling.
PDB ID: 2HACDownload
MMDB ID: 42248
PDB Deposition Date: 2006/6/12
Updated in MMDB: 2007/11
Experimental Method:
solution nmr
Source Organism:
Similar Structures:
Molecular Components in 2HAC
Label Count Molecule
Proteins (2 molecules)
T-cell Surface Glycoprotein CD3 Zeta Chain(Gene symbol: CD247)
Molecule annotation
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Citing MMDB