Ness S A, Weiss R L
J Biol Chem. 1985 Nov 15;260(26):14355-62.
Neurospora crassa contains two carbamoyl-phosphate synthetases: a mitochondrial enzyme (CPS-A) which supplies carbamoyl phosphate for arginine biosynthesis, and a nuclear enzyme whose product is used for the synthesis of pyrimidines. We have prepared antiserum against a highly purified preparation of the large subunit of CPS-A and have used the antiserum to demonstrate that the large subunit is, like most mitochondrially localized proteins, initially synthesized as a higher molecular weight precursor. The CPS-A antiserum cross-reacts with the nuclear enzyme, allowing us to identify the product of the complex N. crassa pyr-3 genetic locus as a protein with a subunit molecular weight of 180,000. Finally, we have found that the CPS-A antiserum also cross-reacts with carbamoyl-phosphate synthetases from bacteria, yeast, and mammals. The immunological relatedness of carbamoyl-phosphate synthetases from such diverse species suggests that the protein sequences required for carbamoyl phosphate production have been highly conserved during the course of evolution.
一种是线粒体酶（CPS-A），它为精氨酸生物合成提供氨甲酰磷酸；另一种是核酶，其产物用于嘧啶的合成。我们制备了针对高度纯化的CPS-A大亚基制剂的抗血清，并使用该抗血清证明，大亚基与大多数线粒体定位蛋白一样，最初是以更高分子量的前体形式合成的。CPS-A抗血清与核酶发生交叉反应，使我们能够将粗糙脉孢菌复杂的pyr-3基因座的产物鉴定为一种亚基分子量为180,000的蛋白质。最后，我们发现CPS-A抗血清也与来自细菌、酵母和哺乳动物的氨甲酰磷酸合成酶发生交叉反应。来自如此不同物种的氨甲酰磷酸合成酶的免疫相关性表明，在进化过程中，氨甲酰磷酸产生所需的蛋白质序列一直高度保守。
