EXPRESSION OF ELONGATION-FACTOR 1-ALPHA (EF-1-ALPHA) AND 1-BETA-GAMMA(EF-1-BETA-GAMMA) ARE UNCOUPLED IN EARLY XENOPUS-EMBRYOS

In the amphibian Xenopus laevis, the elongation factor 1 alpha protein s (EF-1 alpha) synthesised in oocytes and somatic cells correspond to distinct gene products. Furthermore, the somatic EF-1 alpha gene (EF-1 alpha S) produces one of the most highly expressed early zygotic tran scripts in the embryo. The functional recycling of EF-1 alpha (convers ion of EF-1 alpha-GDP to EF-1 alpha-GTP) is assured by the EF-1 beta g amma complex. We show here that in Xenopus laevis embryos, contrary to the situation for EF-1 alpha, EF-1 beta, and EF-1 gamma mRNAs are tra nscribed from the same genes in oocytes and somatic cells. In addition , the onset of transcription of the EF-1 beta and EF-1 gamma genes fro m the zygotic genome occurs several hours after that of the somatic EF -1 alpha S gene. Therefore, during early Xenopus development the expre ssion of these three elongation factors is not co-ordinated at the tra nscriptional level. The consequences of this uncoupling on the efficie ncy of translational elongation in the early Xenopus embryo are discus sed. (C) 1993 Wiley-Liss, Inc.