Functional regions of ornithine decarboxylase antizyme.

Degradation of ornithine decarboxylase, a key enzyme in polyamine biosynthesis, is accelerated by the binding of antizyme, an ornithine decarboxylase inhibitory protein induced by polyamines. In the present study, we examined the effects of a series of deletion mutants of rat antizyme. The results indicated that two regions of antizyme, one internal (amino acids 122-144) and the other near the C-terminus (amino acids 211-218) are necessary for its binding to ornithine decarboxylase and inhibition of its activity, and an additional internal region (amino acids 88-118, especially 113-118) is necessary for its destabilization.