Voss A, Reinhart G, Hogan S, Roehrig K
Department of Food Science and Nutrition, Ohio State University, Columbus 43210.
Biochem Biophys Res Commun. 1987 Nov 30;149(1):118-24. doi: 10.1016/0006-291x(87)91612-3.
The activities of two enzymes involved in the lipogenic process, ATP citrate lyase and NADP-linked malic enzyme were evaluated as a function of cell density in isolated rat hepatocytes. The activity of ATP citrate lyase was profoundly affected by cell density with the activity/cell being higher at low cell densities than at high cell densities. Malic enzyme was not similarly affected, nor was cellular ATP content. The effect was observed regardless of dietary state but was most dramatic with hepatocytes from fasted-refed rats. Both an activator and an inhibitor of ATP citrate lyase have been isolated from conditioned medium from cells at low density and at high density, respectively. The activator fraction was heat stable while the inhibitor fraction was heat labile, and both factors had molecular weights in excess of 10,000 daltons.
在分离的大鼠肝细胞中，评估了参与脂肪生成过程的两种酶——ATP柠檬酸裂解酶和NADP连接的苹果酸酶的活性与细胞密度的关系。ATP柠檬酸裂解酶的活性受细胞密度的影响很大，单位细胞的活性在低细胞密度时高于高细胞密度时。苹果酸酶没有受到类似影响，细胞ATP含量也没有受到影响。无论饮食状态如何，均观察到这种效应，但在禁食-再喂养大鼠的肝细胞中最为明显。分别从低密度和高密度细胞的条件培养基中分离出了ATP柠檬酸裂解酶的激活剂和抑制剂。激活剂部分热稳定，而抑制剂部分热不稳定，且这两种因子的分子量均超过10,000道尔顿。
