All translation elongation factors and the e, f, and h subunits of translation initiation factor 3 are encoded by 5'-terminal oligopyrimidine (TOP) mRNAs.
Terminal oligopyrimidine (TOP) mRNAs (encoded by the TOP genes) are identified by a sequence of 6-12 pyrimidines at the 5' end and by a growth-associated translational regulation. All vertebrate genes for the 80 ribosomal proteins and some other genes involved, directly or indirectly, in translation, are TOP genes. Among the numerous translation factors, only eEF1A and eEF2 are known to be encoded by TOP genes, most of the others having not been analyzed. Here, we report a systematic analysis of the human genes for translation factors. Our results show that: (1) all five elongation factors are encoded by TOP genes; and (2) among the initiation and termination factors analyzed, only eIF3e, eIF3f, and eIF3h exhibit the characteristics of TOP genes. Interestingly, these three polypeptides have been recently shown to constitute a specific subgroup among eIF3 subunits. In fact, eIF3e, eIF3f, and eIF3h are the part of the functional core of eIF3 that is not conserved in Saccharomyces cerevisiae. It has been hypothesized that they are regulatory subunits, and the fact that they are encoded by TOP genes may be relevant for their function.
Iadevaia
Valentina
V
Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy,
Caldarola
Sara
S
Tino
Elisa
E
Amaldi
Francesco
F
Loreni
Fabrizio
F
D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D039621:Eukaryotic Initiation Factor-3 / Q000235:genetics*; D005815:Genetic Code; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D041681:NIH 3T3 Cells; D021122:Protein Subunits / Q000235:genetics; D038641:RNA 5' Terminal Oligopyrimidine Sequence / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics
D039621:Eukaryotic Initiation Factor-3; D021122:Protein Subunits; D012333:RNA, Messenger