Disease relevance of CAF20

• In addition, we show that the amount of poly(A) binding protein (PABP) present in eIF4F complexes decreases during rotavirus infection, even though eIF4A and eIF4E remain unaffected [1].

High impact information on CAF20

• Here we report genetic and biochemical evidence that the yeast translation initiation factor eIF4G associates with CBC, and that eIF4E, the eIF4F component that binds both the cap and eIF4G, antagonizes this interaction [2].
• The eukaryotic mRNA decapping protein Dcp1 interacts physically and functionally with the eIF4F translation initiation complex [3].
• The eukaryotic initiation factor complex eIF4F, which in yeast contains the core components eIF4E and eIF4G, uses the cap as a binding site, serving as an initial point of assembly for the translation apparatus, and also binds the poly(A) binding protein Pab1 [3].
• 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 eIF4F, which carries the binding site for eIF4E [4].
• Specifically, we find that Pab1p co-purifies and co-immunoprecipitates with the eIF-4G subunit of eIF-4F [5].

Biological context of CAF20

• Serum stimulation of cultured Xenopus kidney cells results in enhanced phosphorylation of the translational initiation factor (eIF) 4E and promotes a 2.8-fold increase in the binding of the adapter protein eIF4G to eIF4E, to form the functional initiation factor complex eIF4F [6].
• We have characterized a new type of histidine triad (HIT) motif protein (Nhm1) that co-purifies with the cap-binding complex eIF4F of Schizosaccharomyces pombe [7].
• Three types of observation suggest how changes in the functional status of eIF4F modulate mRNA stability in vivo [8].
• We have found that disruption of the genes for either of the yeast 4E-BPs (Eap1p or Caf20p) leads to an inhibition of pseudohyphal growth in the resulting diploid yeast strain following nitrogen limitation [9].
• These data suggest that at least some functions of plant eIFiso4F and eIF4F have diverged in that eIFiso4F promotes translation preferentially from unstructured mRNAs, whereas eIF4F can promote translation also from mRNAs that contain a structured 5'-leader and that are uncapped or contain multiple cistrons [10].

Anatomical context of CAF20

• Characterisation of the relationship between decapping and interactions involving eIF4F is an essential step towards understanding polysome disassembly and mRNA decay [8].
• The mRNA cap-binding protein eIF4E is the limiting factor in the eIF4F translation initiation complex, which mediates the binding of the 40S ribosome to the mRNA [11].

Associations of CAF20 with chemical compounds

• Identification of Translational Regulation Target Genes during Filamentous Growth in Saccharomyces cerevisiae: Regulatory Role of Caf20 and Dhh1 [12].

Physical interactions of CAF20

• Efficient translation of an SSA1-derived heat-shock mRNA in yeast cells limited for cap-binding protein and eIF-4F [13].
• Signalling events acting on 4E-BP cause it to dissociate from eIF4E, and eIF4E is then free to bind eIF4G to form the active eIF4F complex [14].

Regulatory relationships of CAF20

• The filamentation defects caused by caf20 and dhh1 mutations were suppressed by STE12 overexpression [12].
• In wheat germ, the combination of eIF-4A and eIF-4F resulted in RNA unwinding in a reaction that was stimulated by eIF-4B [15].

Other interactions of CAF20

• In Saccharomyces cerevisiae, the cap-binding protein eIF4E is mainly associated with eIF4G, forming the cap-binding complex eIF4F [16].
• Here we present biochemical data that show that the proteins bound to the mRNA cap (eIF-4F) and poly(A) tail (Pab1p) are physically associated in extracts from the yeast Saccharomyces cerevisiae [5].
• Efficient Ssa1-LacZ polypeptide synthesis was also seen during eIF-4F limitation produced by disruption of the TIF4631 gene, encoding the large eIF-4F subunit [13].
• Recombinant Pdcd4 specifically inhibited the helicase activity of eIF4A and eIF4F [17].
• Ribosome binding to eukaryotic mRNAs requires the concerted action of three eukaryotic initiation factors: eIF-4A, eIF-4B and eIF-4F as well as the hydrolysis of ATP [15].

References