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Last Visited: 5/16/2009
"What's most striking to me, because I'm a yeast geneticist, is that you'd be able to see this effect on feeding behavior," Alan Hinnebusch of the National Institutes of Health, who was not involved in the study, told The Scientist.
In yeast, a deficiency of a particular amino acid causes an accumulation of that amino acid's corresponding transfer RNA.
This free tRNA
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Using amino alcohols to reduce amino acid sensing shows that uncharged tRNA is likely the activating ligand, just as in yeast, said Hinnebusch.
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"It fits perfectly with everything else that's been done in yeast that these alcohol treatments are leading to uncharged tRNA and that's activating GCN2 and eIF-2 phosphorylation," said Hinnebusch.
However, he is "a bit skeptical" that Gietzen and her colleagues can be sure that GCN2 is responsible for changes in feeding behavior.
The data suggesting that GCN2-null mice do not recognize an amino acid-deficient diet do not reveal "that big of a difference," Hinnebusch said.
In addition to measuring the knockouts' response to threonine-devoid food, "it would have been nice to repeat it using some of the alcohols," Hinnebusch said.
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Alan Hinnebusch