Smith K, Ganschow R E
J Biol Chem. 1978 Aug 10;253(15):5437-42.
The turnover properties of murine beta-glucuronidase in several tissues and at two subcellular sites have been determined by monitoring the radioactivity present in immunoprecipitated enzyme at a number of time points following the in vivo administration of a single radiolabeled protein precursor (either L-[3,4(-3H)]leucine or or NaH14CO3). In all experiments a considerable period of time was required for the attainment of maximum specific radioactivity in glucuronidase. Similar labeling kinetics was found when [3H]leucine incorporation was monitored in immunoprecipitated murine liver delta-aminolevulinate dehydratase. Half-life estimates of 2 to 3 days were obtained for glucuronidases of liver, kidney, and spleen. In most strains of inbred mice, it is known that approximately 60% of total liver glucuronidase activity resides in lysosomes, while 40% is within the membranes of the endoplasmic reticulum (Ganschow, R. E. and Paigen, K. (1968) Genetics 59, 335-349). These two subcellular forms of glucuronidase turn over at similar rates. Furthermore, the bulk of glucuronidase in the endoplasmic reticulum does not serve as precursor to lysosomal glucuronidase.
通过在体内给予单一放射性标记的蛋白质前体（L-[3,4(-3H)]亮氨酸或NaH14CO3）后的多个时间点监测免疫沉淀酶中存在的放射性，已确定了小鼠β-葡萄糖醛酸酶在几种组织和两个亚细胞部位的周转特性。在所有实验中，葡萄糖醛酸酶达到最大比放射性需要相当长的时间。当在免疫沉淀的小鼠肝脏δ-氨基乙酰丙酸脱水酶中监测[3H]亮氨酸掺入时，发现了类似的标记动力学。肝脏、肾脏和脾脏的葡萄糖醛酸酶的半衰期估计为2至3天。在大多数近交系小鼠中，已知肝脏总葡萄糖醛酸酶活性的约60%存在于溶酶体中，而40%在内质网的膜内（甘绍，R.E.和派根，K.（1968年）遗传学59，335-349）。葡萄糖醛酸酶的这两种亚细胞形式以相似的速率周转。此外，内质网中的大部分葡萄糖醛酸酶不作为溶酶体葡萄糖醛酸酶的前体。
