Translocation and aggregation of hepatic glycogen synthase during the fasted-to-refed transition in rats
Translocation and aggregation of hepatic glycogen synthase during the fasted-to-refed transition in rats
复制标题
DOI：
10.1111/j.1432-1033.1996.0570z.x
复制
发表时间：
1996-06-01
期刊：
影响因子：
--
通讯作者：
Guinovart, JJ
中科院分区：
文献类型：
--
作者：
FernandezNovell, JM;Roca, A;Guinovart, JJ
本文研究了大鼠从禁食到再进食过程中肝糖原合成酶的激活状态和细胞内分布的变化。取肝匀浆9200g离心后，取上清液和颗粒，测定糖原合成酶活性和活化状态。糖原合成酶活性比呈时间依赖性增加，上清液中酶总活性下降，微丸中酶总活性定量恢复。因此，再投喂诱导了糖原合成酶的激活及其从可溶性部分到颗粒部分的移位。免疫细胞化学证据表明，再投喂诱导了糖原合成酶簇的形成，这些簇在9300a的沉积物中被回收，但酶簇并不与可丸化组分中的糖原颗粒定位。糖原合成酶激活状态对细胞内葡萄糖6-磷酸浓度在0.2-0.3 mM范围内的变化几乎起到开关的作用。小球中存在的酶的数量与细胞内葡萄糖6-磷酸水平呈线性相关。这些结果表明，葡萄糖6-磷酸是体内肝糖原合成酶激活和细胞内定位变化的关键信号。
Changes in the activation state and intracellular distribution of liver glycogen synthase have been studied during the fasted-to-refed transition in rats. Glycogen synthase activity and activation state were measured in supernatants and pellets obtained after centrifugation of liver homogenates at 9200 g. Upon refeeding. the glycogen synthase activity ratio increased, in a time-dependent manner, in both fractions, The total activity of the enzyme decreased in supernatants and was quantitatively recovered in the pellets. Therefore, refeeding induced both the activation of glycogen synthase and its translocation from the soluble to the pelletable fraction. Immunocytochemical evidence indicates that refeeding induced the formation of clusters of glycogen synthase, which were recovered in the 9300 a sediments, However, the enzyme clusters did not locate with the glycogen particles in the pelletable fraction. The glycogen synthase activation state responded almost as an on-off switch to changes in the intracellular glucose 6-phosphate concentration in the range 0.2-0.3 mM. The amount of enzyme present in the pellets correlated linearly with the intracellular glucose 6-phosphate levels. These results indicate that glucose 6-phosphate is the key signal for both the activation and changes in intracellular localization of hepatic glycogen synthase in vivo.