Regulation of the degradation of 125I‐labeled glutamine synthetase introduced into cultured hepatoma cells by erythrocyte ghost—mediated injection
Regulation of the degradation of 125I‐labeled glutamine synthetase introduced into cultured hepatoma cells by erythrocyte ghost—mediated injection
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红细胞血影介导注射引入培养肝癌细胞中 125I 标记谷氨酰胺合成酶降解的调控
DOI：
10.1016/0014-5793(81)81080-0
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发表时间：
1981
期刊：
影响因子：
3.5
通讯作者：
R. G. Kulka
中科院分区：
文献类型：
--
作者：
Aliza Freikopf;R. G. Kulka
The glutamine synthetase (L-glutamate: ammonia ligase (ADP) EC 6.3. 1.2) activity of many mammalian cells in culture decreases with increasing glutamine concentrations in the medium [l-4]. Radioimmunoprecipitation experiments with hepatoma tissue culture (HTC) cells have shown that glutamine decreases glutamine synthetase activity by specifically accelerating the degradation of the enzyme [5]. Although a considerable amount of information has been obtained about the properties of the glutamine synthetase degradation system [4-81, details of the pathway of degradation of the enzyme are still unknown, An obstacle to the elucidation of this pathway has been the failure to obtain glutamine-modulated breakdown of glutamine-synthetase in cell-free systems (unpublished). An alternative approach is to introduce labeled enzyme into unlabeled cells by an injection procedure and to study its degradation in vivo. Here, we have microinjected ‘251-labeled rat liver glutamine synthetase into HTC cells by erythrocyte ghost-mediated injection [9], and could demonstrate that glutamine specifically accelerates its degradation. Pepstatin, a peptide prottease inhibitor impermeable to the cells, was coinjected with 12’1-glutamine synthetase and its effects on the degradation of the enzyme were investigated.
