Russell D H, Manen C A
Biochem Pharmacol. 1982 Nov 1;31(21):3373-8. doi: 10.1016/0006-2952(82)90614-1.
Purified ornithine decarboxylase (EC 4.1.1.17, ODC) transamidated with four putrescine moieties on four glutamine residues through the action of transglutaminase (EC 2.3.2.13, TGase) purified from guinea pig liver, when added to isolated rat liver nuclei, stoichiometrically increased the activity of RNA polymerase I (EC 2.7.7.6). The increase was relative to the pmoles of purified conjugated ODC added to the reaction and could be reinitiated after the reaction had plateaued by the further addition of ODC-putrescine conjugate. The kinetics of the reaction suggest that the ODC-putrescine conjugate was not reused but degraded after each initiation. Otherwise, the rapid plateau would not be observed. The repeated addition of 278 pmoles of purified ODC-putrescine conjugate to rat liver nuclear preparations containing 200 micrograms total protein consistently stimulated the incorporation of 600-700 pmoles UMP/mg protein. We suggest that ODC transamidated by its product putrescine may be the posttranslationally modified 65,000 Mr protein which has been reported by several laboratories to serve as a labile subunit of RNA polymerase I.
经从豚鼠肝脏中纯化的转谷氨酰胺酶（EC 2.3.2.13，TGase）作用，在四个谷氨酰胺残基上与四个腐胺部分进行转酰胺化反应的纯化鸟氨酸脱羧酶（EC 4.1.1.17，ODC），当添加到分离的大鼠肝细胞核中时，能化学计量地增加RNA聚合酶I（EC 2.7.7.6）的活性。这种增加与添加到反应中的纯化共轭ODC的皮摩尔数相关，并且在反应达到平稳期后，通过进一步添加ODC - 腐胺共轭物可以重新引发反应。反应动力学表明，ODC - 腐胺共轭物在每次引发后不会被重新利用而是被降解。否则，不会观察到快速的平稳期。向含有200微克总蛋白的大鼠肝细胞核制剂中重复添加278皮摩尔的纯化ODC - 腐胺共轭物，持续刺激600 - 700皮摩尔UMP/毫克蛋白的掺入。我们认为，被其产物腐胺转酰胺化的ODC可能是几个实验室报道的作为RNA聚合酶I不稳定亚基的65000道尔顿的翻译后修饰蛋白。
