Katz N R, Giffhorn S
Biochem J. 1983 Apr 15;212(1):65-71. doi: 10.1042/bj2120065.
ATP citrate lyase, which is involved in the translocation of the lipogenic precursor acetyl-CoA from mitochondria to cytosol, was studied in primary cultures of hepatocytes from adult rats. After an initial decrease at the first day of culture the enzyme activity was nearly constant during the following days. It could be enhanced between 24h and 48 h in culture about 1.5-fold by elevation of the insulin concentration to 10-7mol/1.22-fold by elevation of the glucose concentration from 5 to 25 mmol/l and 3.5-fold by simultaneous elevation of insulin and glucose. The increase of activity was about linear with time for 24 h and could be blocked by cycloheximide, which inhibits protein synthesis at the translational level. Both observations suggest that the enhancement of activity was due to induction rather than to activation by interconversion. The glucose-dependent induction was furthermore evidenced by immunotitration which indicated a parallel increase of activity and enzyme protein.
在成年大鼠肝细胞原代培养物中对参与将生脂前体乙酰辅酶A从线粒体转运至细胞质的ATP柠檬酸裂解酶进行了研究。在培养第一天酶活性最初下降之后，在接下来的几天里该酶活性几乎保持恒定。将胰岛素浓度提高至10⁻⁷mol/L，可在培养24小时至48小时内使酶活性增强约1.5倍；将葡萄糖浓度从5mmol/L提高至25mmol/L，可使酶活性增强2.2倍；同时提高胰岛素和葡萄糖浓度，可使酶活性增强3.5倍。活性增加在24小时内随时间大致呈线性，且可被在翻译水平抑制蛋白质合成的环己酰亚胺所阻断。这两个观察结果均表明活性增强是由于诱导而非通过相互转化激活所致。此外，免疫滴定法证明了葡萄糖依赖性诱导，该方法表明活性和酶蛋白呈平行增加。
