InterPro domain: IPR007051

Cysteine- and histidine-rich domains (CHORDs) are 60-amino acid modules that bind two zinc ions. They are usually arranged in tandem and are found in all tested eukaryotes, with the exception of yeast, where they are involved in processes ranging from pressure sensing in the heart to maintenance of diploidy in fungi, and exhibit distinct protein-protein interaction specificity. Six cysteine and two histidine residues are invariant within the CHORD domain. Three other residues are also invariant and some positions are confined to positive, negative, or aromatic amino acids [ 1 , 2 ].

Silencing of the Caenorhabditis elegans CHORD-containing gene results in semisterility and embryo lethality, suggesting an essential function of the wild-type gene in nematode development. The CHORD domain is sometimes found N-terminal to the CS domain, IPR007052 , in metazoan proteins, but occurs separately from the CS domain in plants. This association is thought to be indicative of an functional interaction between CS and CHORD domains [ 3 ].

1. A novel class of eukaryotic zinc-binding proteins is required for disease resistance signaling in barley and development in C. elegans. Cell 99, 355-66
2. Biochemical characterization of RAR1 cysteine- and histidine-rich domains (CHORDs): a novel class of zinc-dependent protein-protein interaction modules. Biochemistry 46, 1612-23