Two different mRNAs coding for identical elongation factor 1 alpha (EF-1 alpha) polypeptides in Xenopus laevis embryos

Abstract

Two related but clearly different cDNA clones corresponding to elongation factor 1 alpha (EF-1 alpha) mRNAs were isolated from a Xenopus laevis gastrula-stage library. Whereas the nucleotide sequences of these two cDNAs differ within the coding region at 49 out of 1386 positions (3.5%), the derived amino acid sequences are completely identical, thereby indicating a substantial evolutionary constraint on this translation factor. Southern-blot analysis of genomic DNA suggests that, besides the two closely related EF-1 alpha genes investigated in this study, other more-distantly related genes may exist in the X. laevis genome. Transcription of EF-1 alpha genes during oogenesis and embryonic development was studied by Northern-blot analysis and by in situ hybridizations. A high amount of EF-1 alpha mRNA was detected in previtellogenic oocytes. At later stages of embryonic development, EF-1 alpha mRNA was found to be accumulated in translationally active tissues.