Properties of the ternary complex formed by yeast eIF4E, p20 and mRNA.

Yeast p20 is a small, acidic protein that binds eIF4E, the cap-binding protein. It has been proposed to affect mRNA translation and degradation, however p20's function as an eIF4E-binding protein (4E-BP) and its physiological significance has not been clearly established. In this paper we present data demonstrating that p20 is capable of binding directly to mRNA due to electrostatic interaction of a stretch of arginine and histidine residues in the protein with negatively charged phosphates in the mRNA backbone.

The eIF2A knockout mouse.

Eukaryotic initiation factor 2A (eIF2A) is a 65-kDa protein that was first identified in the early 1970s as a factor capable of stimulating initiator methionyl-tRNAi (Met-tRNA) binding to 40S ribosomal subunits in vitro. However, in contrast to the eIF2, which stimulates Met-tRNA binding to 40S ribosomal subunits in a GTP-dependent manner, eIF2A didn't reveal any GTP-dependence, but instead was found to direct binding of the Met-tRNA to 40S ribosomal subunits in a codon-dependent manner. eIF2A appears to be highly conserved across eukaryotic species, suggesting conservation of function in evolution.