Hepatic glutaminase expression: relationship to kidney-type glutaminase and to the urea cycle.
Hepatic glutaminase expression: relationship to kidney-type glutaminase and to the urea cycle.
复制标题
肝谷氨酰胺酶表达：与肾型谷氨酰胺酶和尿素循环的关系。
DOI：
10.1096/fasebj.7.15.8262331
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Watford,M
中科院分区：
文献类型：
--
作者：
Watford,M
谷氨酰胺作为体内氮和碳的主要运输形式发挥作用。在肝脏中，谷氨酰胺被一种独特的肝型磷酸活化谷氨酰胺酶水解，肝谷氨酰胺催化剂的终产物是葡萄糖和尿素。其他组织具有不同的肾型转氨酶同工酶。预测的氨基酸序列的两个精氨酸酶表现出高度的同一性，表明它们是不同的，但相关的基因的产物。肝转氨酶活性在糖尿病、饥饿和高蛋白饮食中增加，在低蛋白饮食中降低，而肾转氨酶似乎仅受酸碱状态变化的调节。基因转录速率的变化是负责肝转氨酶长期调节的主要机制，但肾酶在mRNA周转水平上受到调节。肝谷氨酰胺酶的调节模式与编码胚胎发生和尿素合成关键酶的基因相似，并表明表达的协调调节与肝谷氨酰胺催化剂在这些途径中的作用一致。Watford，M.肝转氨酶表达：与肾型转氨酶和尿素循环的关系。FASEB J.7：1468 - 1474; 1993。
Glutamine functions as a major transport form of nitrogen and carbon within the body. In the liver, glutamine is hydrolyzed by a unique liver‐type, phosphate‐activated glutaminase, and the end products of hepatic glutamine catabolism are glucose and urea. Other tissues possess a different, kidney‐type, glutaminase isozyme. The predicted amino acid sequences for the two glutaminases show a high degree of identity, indicating that they are products of different but related genes. Hepatic glutaminase activity is increased during diabetes, starvation, and on feeding high‐protein diets, and decreased on feeding low‐protein diets, whereas renal glutaminase appears to be regulated only by changes in acid‐base status. Changes in the rate of gene transcription are the principal mechanism responsible for the long‐term regulation of hepatic glutaminase, but the renal enzyme is regulated at the level of mRNA turnover. The pattern of regulation of hepatic glutaminase parallels that seen for genes encoding key enzymes of gluconeogenesis and urea synthesis, and indicates coordinate regulation of expression in keeping with the role of hepatic glutamine catabolism in these pathways.— Watford, M. Hepatic glutaminase expression: relationship to kidney‐type glutaminase and to the urea cycle.FASEB J.7: 1468‐1474; 1993.