Murakami Y, Ichiba T, Matsufuji S, Hayashi S
Department of Biochemistry 2, The Jikei University School of Medicine, Minato-ku, Tokyo 105, Japan.
J Biol Chem. 1996 Feb 16;271(7):3340-2. doi: 10.1074/jbc.271.7.3340.
The degradation of ornithine decarboxylase (ODC) catalyzed by the 26 S proteasome is accelerated by antizyme, an ODC inhibitory protein induced by polyamines. Previously, we have found another possible regulatory protein of ODC degradation, antizyme inhibitor. Antizyme inhibitor binds to the antizyme with a higher affinity than that of ODC, releasing ODC from ODC-antizyme complex. We report here the cDNA sequence of rat heart antizyme inhibitor. The deduced sequence of the protein is highly similar to, but distinct from, sequences of ODCs from various species. Antizyme inhibitor contains amino acid residues required for formation of active sites of ODC, but it completely lacks ODC activity. Antizyme inhibitor has no homology with peptide sequence in the mammalian ODC carboxyl terminus, which is needed for rapid turnover of ODC. It inhibits antizyme-dependent ODC degradation, but, unlike ODC, its degradation is not accelerated by antizyme.
由26S蛋白酶体催化的鸟氨酸脱羧酶（ODC）降解可被抗酶加速，抗酶是一种由多胺诱导产生的ODC抑制蛋白。此前，我们发现了另一种可能参与ODC降解调控的蛋白——抗酶抑制剂。抗酶抑制剂与抗酶的结合亲和力高于与ODC的结合亲和力，能使ODC从ODC-抗酶复合物中释放出来。我们在此报告大鼠心脏抗酶抑制剂的cDNA序列。该蛋白的推导序列与来自不同物种的ODC序列高度相似，但又有所不同。抗酶抑制剂含有形成ODC活性位点所需的氨基酸残基，但完全缺乏ODC活性。抗酶抑制剂与哺乳动物ODC羧基末端的肽序列没有同源性，而该肽序列是ODC快速周转所必需的。它能抑制抗酶依赖的ODC降解，但与ODC不同的是，其降解不会被抗酶加速。
