Global alterations in translation rates are usually achieved by modifications of general translation initiation factors, such as the phosphorylation of eIF-2a in response to heat shock, viral infections or heme depletion@), the degradation of the p220 subunit of eIF-4F after poliovirus infection@)), or the reduced phosphorylation of elF-4E following serum starvation(I0). Such modifications of translation factors may, however, under some circumstances also imply a competitive advantage of certain mRNAs to be translated. For example, mRNAs with specific structural features in their 5' UTR have been identified which are lcss affccted by reduced activities oTcIF-4E and elF-4F than inost other cellular rnRNAs('l1. In a well characterized system, initiation factor impairment (eIF-2a phosphorylation) actually stimulates the translation of a particular transcript, the yeast GCN4 mRNA('2,13). It wems that eIF-2a phosphorylation 'seduces' the translation apparatus to scan past three short upstream ORFs (uORFs) after translating the first uORF, and to reinitiate translation at the main GCN4 protein reading frame further downstream, which otherwise would not be translated. Thus, global control of protein synthesis and the translational regulation of specific rnRNAs can be interconnected.