Hi Nicola,
It is quite unusual indeed to find zinc ions coordinated by multiple protein chains in the PDB. Some clear examples of tetrahedral zinc sites where the ligands are cysteines and/or histidines include 2a5h (Cys4), 1s1g and 2nz0 (Cys3His1), 3vhs (Cys2His2), 3mo0 (Cys1His3) and the His4 sites in 3c62, 3c63 and 3m15. The His4 sites are composed of residues from 3 chains. For the sites that include cysteines, three of the four zinc-coordinating residues are from the same chain. In all of the entries above the zinc ions are coordinated by residues from (a different copy of) the same protein.
3c62 and 3c63 might be of particular interest to you (their entry title is "Tetrameric Cytochrome cb562 (K34/H59/D62/H63/H73/A74/H77) Assembly Stabilized by Interprotein Zinc Coordination").
Cheers,
Wouter Touw
Postdoctoral fellow
Netherlands Cancer Institute
> Op 17 mei 2016 om 19:09 heeft Nicola Evans <[log in to unmask]> het volgende geschreven:
>
> Hello all, I wanted to ask the community if anyone has come across a structure with a zinc finger where 1 of the 4 zinc-coordinating residues is from separate protein? In a homo or heterodimer?
>
> Thanks in advance.
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