Murine Elongation factor 1α (EF-1α) is posstranslationally modified by novel amide-linked ethanolamine-phosphoglycerol moieties. Addition of ethalanolamine-phosphoglycerol to specific glutamic acid residues on EF-1α

Elongation Factor 1α (EF-1α) an important eukaryotic translation factor, transports charged aminoacyl-tRNA from the cytosol to the ribosomes during polypeptide synthesis. Metabolic radiolabeling with [³H] ethanolamie shows that, in all cells examined, EF-1α is the major radiolabeled protein. Radiolabeled EF-1α has an apparent M(r) = 53,000 and a basic isoelectric point. It is cytosolic and does not contain N-linked oligosaccharides. Trypsin digestion of murine EF-1α generated two major [³H]ethanolamine-labeled peptides. Three peptides were sequenced and were identical to two distinct regions of the human EF-1α protein. Blank sequencing cycles coinciding with glutamic acid in the human cDNA-derived sequence were also found to release [³H]ethanolamine, and compositional analysis of these peptides confirmed the presence of glutamic acid. Dansylation analysis demonstrates that the amine group of the ethanolamine is blocked. These results indicate that EF-1α is posttranslationally modified by the covalent attachment of ethanolamine via an amide bond to at least two specific glutamic acid residues (Glu-301 and Glu-374). The hydroxyl group of the attached ethanolamine was shown by mass spectrometry and compositional analysis, to be further modified by the addition of a phosphoglycerol unit. This novel posttranslational modification may represent an important alteration of EF-1α, comparable to the regulatory effects of posttranslational methylation of EF-1α lysine residues.