Background of the antigen
OVCA1 is required for the first step in the synthesis of diphthamide, a unique posttranslationally modified histidine found only in translation elongation factor-2 (EEF2; MIM 130610). This modification is conserved from archaebacteria to humans and serves as the target for ADP-ribosylation and inactivation of EEF2 by diphtheria toxin (DT) and Pseudomonas exotoxin A. OVCA1 is one of several enzymes involved in synthesis of diphthamide in EEF2.