Protein required for synthesis of diphthamide%3B required along with Dph2p%2C Kti11p%2C Jjj3p%2C and Dph5p%3B diphthamide is a modified histidine residue of translation elongation factor 2 (Eft1p or Eft2p)%3B may act in a complex with Dph2p and Kti11p