Nonidentity of the 48,000-dalton protein of mRNA-protein particles and the beta subunit of eukaryotic initiation factor 2.

The beta subunits of the GTP-dependent initiator methionyl-tRNA-binding protein and the 48,000-dalton protein, which is one of the two major proteins present in isolated mRNA . protein particles, have been shown to share a number of similar structural and mRNA-binding properties. The nonidentity of these two proteins is now established by documentation of differing molecular weights, isoelectric focusing points, and products of protease or cyanogen bromide cleavage.