Physical evidence for distinct mechanisms of translational control by upstream open reading frames.

ABSTRACT: The Saccharomyces cerevisiae GCN4 mRNA 5'-leader contains four upstream open reading frames (uORFs) and the CPA1 leader contains a single uORF. To determine how these uORFs control translation, we examined mRNAs containing these leaders in cell-free translation extracts to determine where ribosomes were loaded first and where they were loaded during steady-state translation. Ribosomes predominantly loaded first at GCN4 uORF1. Following its translation, but not the translation of uORF4, they efficiently reinitiated protein synthesis at Gcn4p. Adding purified eIF2 increased reinitiation at uORFs 3 or 4 and reduced reinitiation at Gcn4p. This indicates that eIF2 affects the site of reinitiation following translation of GCN4 uORF1 in vitro. In contrast, for mRNA containing the CPA1 uORF, ribos

SUBMITTER: Gaba A 

PROVIDER: S-EPMC125715 | biostudies-literature | 2001 Nov

REPOSITORIES: biostudies-literature