Eukaryotic Translation Initiation Factor 3C (EIF3C)

Eukaryotic initiation factor-3 (eIF3) is the largest of the eIFs and consists of at least 10 nonidentical subunits in mammals. The 115-kD component of HeLa cell eIF3 is actually composed of 2 proteins, p116 (PRT1) and p110. By screening a HeLa cell expression library with antibodies against the 115-kD band, these authors identified cDNAs encoding p110. The predicted 913-amino acid p110 protein has a pI of 5.8 and is unrelated to p116. p110 shares 31% identity to the S. cerevisiae Nip1 protein, which is thought to be involved in nuclear import and the initiation phase of protein synthesis. The p116, p110, and p36 subunits localize on 40S ribosomes in cells active in translation and coimmunoprecipitate with p170, indicating that these proteins are integral components of eIF3.