Shenoy V, Roig J C, Chakrabarti R, Kubilis P, Neu J
Department of Pediatrics, University of Florida College of Medicine, Gainesville 32610, USA.
Pediatr Res. 1996 Apr;39(4 Pt 1):643-8. doi: 10.1203/00006450-199604000-00014.
Glutamine synthetase (GS) is a key enzyme involved in the endogenous biosynthesis of glutamine, an amino acid known to be essential for small intestinal metabolism and function. This study describes the ontogeny of rat small intestinal GS from fetal life through adulthood with enzyme activities, protein immunoblotting, and steady state levels of GS mRNA by RNA gel blots and dot blots. Enzyme activities progressively increased from 21 d of fetal life to 32 d postnatally, then decreased in adulthood. The amount of GS immunoreactive protein in the small intestine increased from fetal life to 10-day-old infants and persisted into adulthood. GS mRNA, as quantified by dot blots was highest at 19 d postnatally. The ontogenic changes in rat small intestinal GS appear to correspond temporally with rapid growth and weaning. The steady increase in GS enzyme activity up to 32 d of age with a subsequent drop in adulthood is not paralleled by an increase in GS mRNA or protein. These findings suggest an apparent complex regulation of the enzyme activity at a transcriptional or translational levels.
谷氨酰胺合成酶（GS）是参与谷氨酰胺内源性生物合成的关键酶，谷氨酰胺是一种已知对小肠代谢和功能至关重要的氨基酸。本研究通过酶活性、蛋白质免疫印迹以及RNA凝胶印迹和斑点印迹法检测GS mRNA的稳态水平，描述了大鼠小肠GS从胎儿期到成年期的个体发生情况。酶活性从胎儿期21天到出生后32天逐渐增加，然后在成年期下降。小肠中GS免疫反应性蛋白的量从胎儿期到10日龄婴儿增加，并持续到成年期。通过斑点印迹法定量的GS mRNA在出生后19天最高。大鼠小肠GS的个体发生变化似乎在时间上与快速生长和断奶相对应。直到32日龄GS酶活性持续增加，随后在成年期下降，这与GS mRNA或蛋白质的增加并不平行。这些发现表明在转录或翻译水平上该酶活性存在明显复杂的调节。
