Diphthine synthase is anenzyme that in humans is encoded by theDPH5gene.[5][6]
This gene encodes a component of thediphthamide synthesis pathway. Diphthamide is a post-translationally modifiedhistidine residue found only on translation elongation factor 2. It is conserved fromarchaebacteria to humans, and is targeted bydiphtheria toxin andPseudomonas exotoxin A to halt cellular protein synthesis.
The yeast andChinese hamster homologs of this protein catalyze the trimethylation of the histidine residue onelongation factor 2, resulting in a diphthine moiety that is subsequently amidated to yield diphthamide. Multiple transcript variants encoding differentisoforms have been found for this gene.[6]
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