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(Received for publication, January 25, 1996, and in revised form, March 14, 1996)
From the Department of Biochemistry and Molecular Biology, Indiana
University School of Medicine, Indianapolis, Indiana 46202-5122
Phosphorylation of the
subunit of eukaryotic
initiation factor-2 (eIF-2) is a well characterized mechanism
regulating protein synthesis. Viral and cellular proteins have been
identified that regulate the activity of the eIF-2
kinases. The
regulatory protein, K3L, from vaccinia virus is homologous to the amino
terminus of eIF-2
and is thought to inhibit the activity of the
double-stranded RNA-dependent kinase suppressing the
antiviral mechanism mediated by this kinase. We investigated whether
K3L can inhibit the activity of the yeast eIF-2
kinase GCN2.
Expression of K3L protein in yeast reduced the level of eIF-2
phosphorylation by GCN2 and blocked the stimulation of the general
amino acid control pathway in response to starvation conditions.
Accompanying in vitro studies showed that recombinant K3L
protein reduced GCN2 autophosphorylation and phosphorylation eIF-2
.
In agreement with the hypothesis that K3L inhibits eIF-2
kinases by
functioning as a pseudosubstrate, we observed that K3L directly
interacted with the kinase catalytic domain of GCN2. Together,
these results indicate that K3L is a specific inhibitor of eIF-2
kinases from mammals and yeast and suggest that the kinases
contain common structural features important for recognition of their
substrate eIF-2
.
This article has been cited by other articles:
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S. Zhu and R. C. Wek Ribosome-binding Domain of Eukaryotic Initiation Factor-2 Kinase GCN2 Facilitates Translation Control J. Biol. Chem., January 16, 1998; 273(3): 1808 - 1814. [Abstract] [Full Text] [PDF] |
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