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Homeobox-cysteine loop-homeobox This domain is considered a double homeodomain, termed HOCHOB, present in the C. elegans genome. Family members include CEH-91 and CEH-93 that share extended sequence similarity with each other upstream of their typical HDs (Homeodomains). CEH-92, another family member, has three copies of this domain. The domain consists of two divergent HDs that are separated by a linker of about 17 residues. The linker has a number of conserved positions, two of which are cysteine residues suggesting that they could be involved in metal binding. Hence, the name HOCHOB (Homeobox-cysteine loop-homeobox). Furthermore, there are two conserved histidine residues, one in each HD (in CEH-91 displaced by two positions), and there is also a conserved aspartic acid. It is speculated that the HOCHOB domain is an evolutionary novelty that is derived from two HDs and may have gained metal-binding capacity. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",