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Biochem J. 1999 Aug 15;342 ( Pt 1):65-70.

Caspase-mediated cleavage of eukaryotic translation initiation factor subunit 2alpha.

Author information

1
Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.

Abstract

Eukaryotic translation initiation factor 2alpha (eIF-2alpha), a target molecule of the interferon-inducible double-stranded-RNA-dependent protein kinase (PKR), was cleaved in apoptotic Saos-2 cells on treatment with poly(I).poly(C) or tumour necrosis factor alpha. This cleavage occurred with a time course similar to that of poly(ADP-ribose) polymerase, a well-known caspase substrate. In addition, eIF-2alpha was cleaved by recombinant active caspase-3 in vitro. By site-directed mutagenesis, the cleavage site was mapped to an Ala-Glu-Val-Asp(300) downward arrowGly(301) sequence located in the C-terminal portion of eIF-2alpha. PKR phosphorylates eIF-2alpha on Ser(51), resulting in the suppression of protein synthesis. PKR-mediated translational suppression was repressed when the C-terminally cleaved product of eIF-2alpha was overexpressed in Saos-2 cells, even though PKR can phosphorylate this cleaved product. These results suggest that caspase-3 or related protease(s) can modulate the efficiency of protein synthesis by cleaving the alpha subunit of eIF-2, a key component in the initiation of translation.

PMID:
10432301
PMCID:
PMC1220437
[Indexed for MEDLINE]
Free PMC Article

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