Organization of a multifunctional protein in pyrimidine biosynthesis. A domain hypersensitive to proteolysis.
Organization of a multifunctional protein in pyrimidine biosynthesis. A domain hypersensitive to proteolysis.
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嘧啶生物合成中多功能蛋白质的组织。
DOI：
10.1042/bj2170435
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Davidson,JN
中科院分区：
文献类型：
--
作者：
Rumsby,PC;Campbell,PC;Niswander,LA;Davidson,JN
当用葡萄球菌V8蛋白酶处理仓鼠细胞中催化前三步嘧啶生物合成的多功能蛋白时，只发生一次裂解。氨甲酰磷酸合成酶（EC 6.3.5.5）、天冬氨酸氨甲酰转移酶（EC 2.1.3.2）和二氢羟化酶（EC 3.5.2.3）的活性和UTP的变构抑制作用均不受影响。Mr 182000的一个片段具有第一和第三酶活性，而Mr 42000的另一个片段具有天冬氨酸氨基甲酰转移酶活性和聚集位点。在用低浓度胰蛋白酶消化的蛋白质中也观察到类似的小片段。在用胰蛋白酶消化后可以看到类似的大片段，并且在某些嘧啶生物合成缺陷的突变体中作为该蛋白质的主要形式。这些结果表明，位于天冬氨酸氨基甲酰转移酶结构域附近的区域在体外对蛋白酶作用敏感，在体内也可能对蛋白酶水解敏感。
When the multifunctional protein that catalyses the first three steps of pyrimidine biosynthesis in hamster cells is treated with staphylococcal V8 proteinase, a single cleavage takes place. The activities of carbamoyl-phosphate synthetase (EC 6.3.5.5), aspartate carbamoyltransferase (EC 2.1.3.2) and dihydro-orotase (EC 3.5.2.3) and the allosteric inhibition by UTP are unaffected. One fragment, of Mr 182000, has the first and third enzyme activities, whereas the other fragment, of Mr 42000, has aspartate carbamoyltransferase activity and an aggregation site. A similar small fragment is observed in protein digested with low concentrations of trypsin. A similar large fragment is seen after digestion with trypsin and as the predominating form of this protein in certain mutants defective in pyrimidine biosynthesis. These results indicate that a region located adjacent to the aspartate carbamoyltransferase domain is hypersensitive to proteinase action in vitro and may also be sensitive to proteolysis in vivo.