Murine elongation factor 1 alpha (EF-1 alpha) is posttranslationally modified by novel amide-linked ethanolamine-phosphoglycerol moieties. Addition of ethanolamine-phosphoglycerol to specific glutamic acid residues on EF-1 alpha.
Elongation Factor 1 alpha (EF-1 alpha), an important eukaryotic translation factor, transports charged aminoacyl-tRNA from the cytosol to the ribosomes during poly-peptide synthesis. Metabolic radiolabeling with [3H] ethanolamine shows that, in all cells examined, EF-1 alpha is the major radiolabeled protein. Radiolabeled EF-1 alpha has an apparent Mr = 53,000 and a basic isoelectric point. It is cytosolic and does not contain N-linked oligosaccharides. Trypsin digestion of murine EF-1 alpha generated two major [3H]ethanolamine-labeled peptides. Three peptides were sequenced and were identical to two distinct regions of the human EF-1 alpha 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-1 alpha 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-1 alpha, comparable to the regulatory effects of posttranslational methylation of EF-1 alpha lysine residues.
Whiteheart
S W
SW
Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Shenbagamurthi
P
P
Chen
L
L
Cotter
R J
RJ
Hart
G W
GW
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D019856:Ethanolamine; D004983:Ethanolamines / Q000378:metabolism*; D005971:Glutamates / Q000235:genetics / Q000378:metabolism*; D018698:Glutamic Acid; D005994:Glycerophosphates / Q000378:metabolism*; D006801:Humans; D013058:Mass Spectrometry; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000302:isolation & purification; D011499:Protein Processing, Post-Translational; D013945:Thymoma / Q000378:metabolism; D014316:Tritium
D004983:Ethanolamines; D005971:Glutamates; D005994:Glycerophosphates; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors; D010446:Peptide Fragments; D014316:Tritium; D018698:Glutamic Acid; D019856:Ethanolamine