Gotoh T, Sonoki T, Nagasaki A, Terada K, Takiguchi M, Mori M
Department of Molecular Genetics, Kumamoto University School of Medicine, Japan.
FEBS Lett. 1996 Oct 21;395(2-3):119-22. doi: 10.1016/0014-5793(96)01015-0.
Arginase exists in two isoforms. Liver-type arginase (arginase I) is expressed almost exclusively in the liver and catalyzes the last step of urea synthesis, whereas the nonhepatic type (arginase II) is expressed in extrahepatic tissues. Arginase II has been proposed to play a role in down-regulation of nitric oxide synthesis. A cDNA for human arginase II was isolated. A polypeptide of 354 amino acid residues including the putative NH2-terminal presequence for mitochondrial import was predicted. It was 59% identical with arginase I. The arginase II precursor synthesized in vitro was imported into isolated mitochondria and proteolytically processed. mRNA for human arginase II was present in the kidney and other tissues, but was not detected in the liver. Arginase II mRNA was coinduced with nitric oxide synthase mRNA in murine macrophage-like RAW 264.7 cells by lipopolysaccharide. This induction was enhanced by dexamethasone and dibutyryl cAMP, and was prevented by interferon-gamma. Possible roles of arginase II in NO synthesis are discussed.
精氨酸酶有两种同工型。肝型精氨酸酶（精氨酸酶I）几乎只在肝脏中表达，催化尿素合成的最后一步，而非肝型（精氨酸酶II）则在肝外组织中表达。有人提出精氨酸酶II在一氧化氮合成的下调中起作用。分离出了人精氨酸酶II的cDNA。预测了一个由354个氨基酸残基组成的多肽，包括推测的用于线粒体导入的NH2末端前序列。它与精氨酸酶I有59%的同源性。体外合成的精氨酸酶II前体被导入分离的线粒体并进行蛋白水解加工。人精氨酸酶II的mRNA存在于肾脏和其他组织中，但在肝脏中未检测到。在鼠巨噬细胞样RAW 264.7细胞中，脂多糖可使精氨酸酶II mRNA与一氧化氮合酶mRNA共同诱导表达。地塞米松和二丁酰环磷腺苷可增强这种诱导作用，而干扰素-γ可抑制这种诱导作用。文中讨论了精氨酸酶II在一氧化氮合成中的可能作用。
