Open AccessTwo functionally redundant isoforms of Drosophila melanogaster eukaryotic initiation factor 4B are involved in cap‐dependent translation, cell survival, and proliferation
Author(s) -
Hernández Greco,
VázquezPianzola Paula,
Zurbriggen Andreas,
Altmann Michael,
Sierra José M.,
RiveraPomar Rolando
Publication year - 2004
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.2004.04217.x
Subject(s) - eif4a , eukaryotic translation , eukaryotic initiation factor , initiation factor , internal ribosome entry site , microbiology and biotechnology , gene isoform , drosophila melanogaster , rna , biology , alternative splicing , translation (biology) , messenger rna , eif4a1 , chemistry , gene , biochemistry
Eukaryotic initiation factor (eIF) 4B is part of the protein complex involved in the recognition and binding of mRNA to the ribosome. Drosophila eIF4B is a single‐copy gene that encodes two isoforms, termed eIF4B‐L (52.2 kDa) and eIF4B‐S (44.2 kDa), generated as a result of the alternative recognition of two polyadeynlation signals during transcription termination and subsequent alternative splicing of the two pre‐mRNAs. Both eIF4B mRNAs and proteins are expressed during the entire embryogenesis and life cycle. The proteins are cytoplasmic with polarized distribution. The two isoforms bind RNA with the same affinity. eIF4B‐L and eIF4B‐S preferentially enhance cap‐dependent over IRES‐dependent translation initiation in a Drosophila cell‐free translation system. RNA interference experiments suggest that eIF4B is required for cell survival, although only a modest reduction in rate of protein synthesis is observed. Overexpression of eIF4B in Drosophila cells in culture and in developing eye imaginal discs promotes cell proliferation.