Studies on Ornithine Decarboxylase Antizyme
Tissue levels of ornithine decarboxylase (ODC) are under negative feedback regulation by polyamines. Thus, exogenously added polyamines cause a rapid decrease of ODC activity. Recent studies in various laboratories have indicated that the rapid decay of ODC activity caused by polyamines is due both to suppression of ODC synthesis (1–3) and to acceleration of ODC degradation (1, 2, 4) and that a new protein synthesis is needed for the latter effect (2). Antizyme was discovered in 1976 by Canellakis and his collaborators as a unique protein inhibitor of ODC induced by polyamines (5, 6). Since then, antizyme has been shown to be present in various tissues and cells as a free form and/or a complex with ODC (7). Previous studies in this and other laboratories have led to a hypothesis that antizyme not only inhibits ODC activity but also accelerates its degradation in a recycling manner (8–10). The strongest evidence for that hypothesis was the existence of a good correlation between ODC decay rate and antizyme/ODC ratio in HTC cells (9). In the present paper, we report the results of our recent studies that support the above hypothesis. We also present some of our results on the cloning of cDNAs for rat liver antizyme.
KeywordsOrnithine Decarboxylase Mouse Kidney Testosterone Enanthate Ornithine Decarboxylase Activity DFMO Treatment
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