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Translational inhibition by eIF‐2‐phospholipid complex in mammalian cell‐free systems
Author(s) -
Pelaez Fernando,
de Haro Cesar
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)80789-6
Subject(s) - reticulocyte , initiation factor , phosphatidic acid , translation (biology) , phosphatidylinositol , biochemistry , protein subunit , biology , chemistry , eukaryotic translation , eukaryotic initiation factor , microbiology and biotechnology , phospholipid , messenger rna , phosphorylation , membrane , gene
The polypeptide chain initiation factor 2 (eIF‐2) binds phospholipid (PL) and becomes a potent inhibitor of translation in hemin‐supplemented reticulocyte lysates [De Haro et al. (1986) Proc. Natl. Acad. Sci. USA 83, 6711–6715]. This binding is independent of calcium ions and seems to be specific for phosphatidylinositol or phosphatidylserine; phosphatidic and arachidonic acids are inactive. Like α‐subunit‐phosphorylated eIF‐2, eIF‐2·PL traps GEF in a non‐dissociable eIF‐2·PL·GEF complex whereby GEF is no longer able to recycle. Initiation is inhibited when no free GEF is available. Translational inhibition by eIF‐2·PL is rescued by equimolar amounts of eIF‐2·GEF. On the basis of this stoichiometry, we have estimated that reticulocyte lysates contain about 60 pmol of GEF/ml (60 nM) eIF‐2·PL also inhibits translation in cell‐free mouse liver extracts and this inhibition is prevented by reticulocyte eIF‐2·GEF suggesting that GEF also functions in liver. However, the eIF‐2·PL complex does not affect translation in such non‐mammalian eukaryotic systems as wheat germ and Drosophila embryos.