Structural elements of ornithine decarboxylase required for intracellular degradation and polyamine-dependent regulation.
Structural elements of ornithine decarboxylase required for intracellular degradation and polyamine-dependent regulation.
复制标题
细胞内降解和多胺依赖性调节所需的鸟氨酸脱羧酶的结构元件。
DOI：
10.1128/mcb.12.5.2178-2185.1992
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发表时间：
1992
影响因子：
5.3
通讯作者：
Coffino,P
中科院分区：
文献类型：
--
作者：
Ghoda,L;Sidney,D;Macrae,M;Coffino,P
Mammalian ornithine decarboxylase (ODC), a key enzyme in polyamine biosynthesis, is rapidly degraded in cells, an attribute important to the regulation of its activity. Mutant and chimeric ODCs were created to determine the structural requirements for two modes of proteolysis. Constitutive degradation requires the carboxy terminus and is independent of intracellular polyamines. Truncation of five or more carboxy-terminal amino acids prevents this mode of degradation, as do several internal deletions within the 37 carboxy-most amino acids that spare the last five residues. Polyamine-dependent degradation of ODC requires a distinct region outside the carboxy terminus. The ODC of a parasite,Trypanosoma brucei, is structurally very similar to mouse ODC but lacks the carboxy-terminal domain; it is not a substrate for either pathway. The regulatory properties of enzymatically active chimeric proteins incorporating regions of the two ODCs support the conclusion that distinct domains of mouse ODC confer constitutive degradation and polyamine-mediated regulation. Mouse ODC contains two PEST regions. The first was not required for either form of degradation; major deletions within the second ablated constitutive degradation. When mouse andT. bruceiODC RNAs were translated in vitro in a reticulocyte lysate system, the effects of polyamine concentration on ODC protein production and activity were similar for the two mRNAs, which contradicts claims that this system accurately reflects the in vivo effects of polyamines on responsive ODCs.
