Involvement of lysosomes in substrate stabilization of tryptophan-2,3-dioxygenase in rat liver.
Administration of tryptophan or hydrocortisone to rats caused a several-fold increase in tryptophan-2,3-dioxygenase activity in the liver. Highly purified lysosomes were isolated from livers of tryptophan- or hydrocortisone-treated animals as well as the control rats. Immunoblotting of lysosomal proteins with anti-tryptophan-2,3-dioxygenase showed 48 kDa band, corresponding to the subunit molecular weight of the enzyme. The relative amount of the immuno-reactive substance in the lysosomes from hydrocortisone-treated rats was 3 times higher than the control while the value in the lysosomes from tryptophan-treated rats was essentially the same as in the control. These results indicate that administration of tryptophan renders cytosolic tryptophan-2,3-dioxygenase less vulnerable to lysosomal uptake and causes an accumulation of the enzyme in the cytosol.
Sato
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A
Department of Nutritional Chemistry, School of Medicine, University of Tokushima, Japan.
Endo
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Y
Natori
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Y
D000818:Animals; D004795:Enzyme Stability; D006854:Hydrocortisone / Q000494:pharmacology*; D008099:Liver / Q000201:enzymology*; D008247:Lysosomes / Q000187:drug effects*; D008297:Male; D051381:Rats; D014364:Tryptophan / Q000494:pharmacology*; D014366:Tryptophan Oxygenase / Q000187:drug effects*
D014364:Tryptophan; D014366:Tryptophan Oxygenase; D006854:Hydrocortisone