Eukaryotic Translation Initiation Factor 4E Binding Protein 3 (EIF4EBP3)

EIF4EBP3 encodes a member of the EIF4EBP family which derives it name from proteins that bind to eukaryotic initiation factor 4E and that prevent its assembly into EIF4F. Co-transcription of this gene and the neighboring upstream gene (MASK) generates a transcript (MASK-BP3) which encodes a fusion protein comprised of the MASK protein sequence for the majority of the protein and a different C-terminus due to an alternate reading frame for the EIF4EBP3 segments.The deduced 100-amino acid protein shares 57% and 59% identity with EIF4EBP1 and EIF4EBP2, respectively. Northern blot analysis detected a major 800-bp transcript in almost every tissue examined, although at varying levels. The authors demonstrated that the 14.6-kD EIF4EBP3 phosphoprotein is heat stable and binds to EIF4E in vitro as well as in vivo.