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The 5' ends of eukaryotic mRNAs are blocked by a cap structure, m7GpppX (where X is any nucleotide). The interaction of the cap structure with a cap-binding protein complex is required for efficient ribosome binding to the mRNA. In Saccharomyces cerevisiae, the cap-binding protein complex is a heterodimer composed of two subunits with molecular masses of 24(More)
Translation initiation factors eIF4A and eIF4G form, together with the cap-binding factor eIF4E, the eIF4F complex, which is crucial for recruiting the small ribosomal subunit to the mRNA 5' end and for subsequent scanning and searching for the start codon. eIF4A is an ATP-dependent RNA helicase whose activity is stimulated by binding to eIF4G. We report(More)
We have cloned and characterized a family of mouse genomic sequences hybridizing to mouse cDNA probes coding for eIF-4A, one of the protein synthesis initiation factors involved in the binding of mRNA to the ribosome. We estimate that there is a total of approximately 9-13 eIF-4A pseudogenes. We also found an eIF-4A intronless retroposon which, when(More)
Characterization of cDNAs encoding eukaryotic translation initiation factor 4A (eIF-4A) indicates the expression of a minimum of ten related genes in tobacco leaf cells. The ten groups fall into two gene families, NeIF-4A2 and NeIF-4A3. The majority of the cDNAs exhibit significant sequence similarity to the NeIF-4A2 family at both the DNA and deduced amino(More)
In the yeast Saccharomyces cerevisiae a small protein named p20 is found associated with translation initiation factor eIF4E, the mRNA cap-binding protein. We demonstrate here that p20 is a repressor of cap-dependent translation initiation. p20 shows amino acid sequence homology to a region of eIF4G, the large subunit of the cap-binding protein complex(More)
BACKGROUND Translation initiation factor 4A (elF4A) is the prototype of the DEAD-box family of proteins. DEAD-box proteins are involved in a variety of cellular processes including splicing, ribosome biogenesis and RNA degradation. Energy from ATP hydrolysis is used to perform RNA unwinding during initiation of mRNA translation. The presence of elF4A is(More)
The translation initiation factor 4E (eIF-4E) is involved in the recognition of the cap structure at the 5' end of eukaryotic mRNA and facilitates ribosome binding. Subsequently, additional initiation factors mediate ribosomal scanning of mRNA and initiator AUG recognition (Shatkin, A. J. (1985) Cell 40, 223-224; Rhoads, R. E. (1988) Trends Biochem. Sci.(More)
Yeast Saccharomyces cerevisiae genes TIF1 and TIF2 (translation initiation factor) encode a protein tentatively called translation initiation factor (Tif) due to the similarity of its amino acid sequence and its molecular weight to mammalian eukaryotic initiation factor 4A. To clarify whether Tif is involved in translation, we produced an affinity-purified(More)
Initiation factor eIF4G is an essential protein required for initiation of mRNA translation via the 5' cap-dependent pathway. It interacts with eIF4E (the mRNA 5' cap-binding protein) and serves as an anchor for the assembly of further initiation factors. With treatment of Saccharomyces cerevisiae with rapamycin or with entry of cells into the diauxic(More)
We have isolated genomic and cDNA clones encoding protein synthesis initiation factor eIF-4E (mRNA cap-binding protein) of the yeast Saccharomyces cerevisiae. Their identity was established by expression of a cDNA in Escherichia coli. This cDNA encodes a protein indistinguishable from purified eIF-4E in terms of molecular weight, binding to and elution from(More)