title: The paradox of elongation factor 4: highly conserved, yet of no physiological significance?
abstract: LepA [EF4 (elongation factor 4)] is a highly conserved protein found in nearly all known genomes. EF4 triggers back-translocation of the elongating ribosome, causing the translation machinery to move one codon backwards along the mRNA. Knockout of the corresponding gene in various bacteria results in different phenotypes; however, the physiological function of the factor in vivo is unclear. Although functional research on Guf1 (GTPase of unknown function 1), the eukaryotic homologue of EF4, showed that it plays a critical role under suboptimal translation conditions in vivo, its detailed mechanism has yet to be identified. In the present review we briefly cover recent advances in our understanding of EF4, including in vitro structural and biochemical studies, and research on its physiological role in vivo. Lastly, we present a hypothesis for back-translocation and discuss the directions future EF4 research should focus on.
authors.affiliation: Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China.
authors.forename: Dejiu
authors.initials: D
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Qin
mesh_terms: D000818:Animals; D017124:Conserved Sequence; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D008958:Models, Molecular; D010441:Peptide Chain Elongation, Translational; D010448:Peptide Initiation Factors; D035602:Transcriptional Elongation Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; C515651:LepA protein, E coli; D010448:Peptide Initiation Factors; D035602:Transcriptional Elongation Factors