Nyunoya H, Broglie K E, Widgren E E, Lusty C J
J Biol Chem. 1985 Aug 5;260(16):9346-56.
The nucleotide sequence of rat carbamyl phosphate synthetase I mRNA has been determined from the complementary DNA. The mRNA comprises minimally 5,645 nucleotides and codes for a polypeptide of 164,564 Da corresponding to the precursor form of the rat liver enzyme. The primary sequence of mature rat carbamyl phosphate synthetase I indicates that the precursor is cleaved at one of two leucines at residues 38 or 39. The derived amino acid sequence of carbamyl phosphate synthetase I is homologous to the sequences of carbamyl phosphate synthetase of Escherichia coli and yeast. The sequence homology extends along the entire length of the rat polypeptide and encompasses the entire sequences of both the small and large subunits of the E. coli and yeast enzymes. The protein sequence data provide strong evidence that the carbamyl phosphate synthetase I gene of rat, the carAB gene of E. coli, and the CPA1 and CPA2 genes of yeast were derived from common ancestral genes. Part of the rat carbamyl phosphate synthetase I gene has been characterized with two nonoverlapping phage clones spanning 28.7 kilobases of rat chromosomal DNA. This region contains 13 exons ranging in size from 68 to 195 base pairs and encodes the 453 carboxyl-terminal amino acids of the rat protein. Southern hybridization analysis of rat genomic DNA indicates the carbamyl phosphate synthetase I gene to be present in single copy.
大鼠氨甲酰磷酸合成酶I mRNA的核苷酸序列已由互补DNA确定。该mRNA最少包含5645个核苷酸，编码一种分子量为164564 Da的多肽，对应大鼠肝脏酶的前体形式。成熟大鼠氨甲酰磷酸合成酶I的一级序列表明，前体在第38或39位的两个亮氨酸之一处被切割。推导的氨甲酰磷酸合成酶I氨基酸序列与大肠杆菌和酵母的氨甲酰磷酸合成酶序列同源。序列同源性沿着大鼠多肽的全长延伸，涵盖了大肠杆菌和酵母酶的小亚基和大亚基的整个序列。蛋白质序列数据提供了有力证据，表明大鼠的氨甲酰磷酸合成酶I基因、大肠杆菌的carAB基因以及酵母的CPA1和CPA2基因源自共同祖先基因。大鼠氨甲酰磷酸合成酶I基因的一部分已通过两个不重叠的噬菌体克隆进行了表征，这两个克隆跨越了28.7千碱基对的大鼠染色体DNA。该区域包含13个外显子，大小从68到195个碱基对不等，编码大鼠蛋白质的453个羧基末端氨基酸。大鼠基因组DNA的Southern杂交分析表明氨甲酰磷酸合成酶I基因以单拷贝形式存在。
