Kalant N, Parniak M, Lemieux M
Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada.
Biochem J. 1987 Dec 15;248(3):927-31. doi: 10.1042/bj2480927.
Rat hepatocytes were incubated with 14C-labelled hexoses, and the specific radioactivities of glucose 6-phosphate, glucose 1-phosphate and fructose 6-phosphate were determined. (1) When suspensions of freshly isolated hepatocytes were incubated with [14C]glucose, the specific radioactivities of glucose 1-phosphate and fructose 6-phosphate were severalfold higher than that of glucose 6-phosphate. The ratios of the specific radioactivities decreased with time of incubation. These relationships were also found when incubations were carried out with primary cultures of rat hepatocytes or with crude homogenates of hepatocytes, but not with isolated nuclei. (2) When cells were incubated with [14C]fructose, the ratios of the specific radioactivities were higher than with [14C]glucose, and also decreased with time. (3) Paired incubations were carried out with a mixture of galactose and fructose, with one or other sugar being labelled with 14C. The specific radioactivity of glucose released into the medium was greater than that of glucose 6-phosphate when fructose was labelled, but not when galactose was labelled. Furthermore, glucose 6-phosphate and glucose in the medium differed with regard to the distribution of 14C between C-1 and C-6. These results are interpreted as evidence that glucose 6-phosphate in hepatocytes does not exist as a homogeneous pool, but that subcompartments exist which are associated with glucose phosphorylation, gluconeogenesis and glycogenolysis.
将大鼠肝细胞与14C标记的己糖一起孵育，并测定6-磷酸葡萄糖、1-磷酸葡萄糖和6-磷酸果糖的比放射性。(1)当将新鲜分离的肝细胞悬液与[14C]葡萄糖一起孵育时，1-磷酸葡萄糖和6-磷酸果糖的比放射性比6-磷酸葡萄糖高几倍。比放射性的比值随孵育时间而降低。当用大鼠肝细胞原代培养物或肝细胞粗匀浆进行孵育时也发现了这些关系，但在分离的细胞核中未发现。(2)当细胞与[14C]果糖一起孵育时，比放射性的比值高于与[14C]葡萄糖一起孵育时，并且也随时间降低。(3)用半乳糖和果糖的混合物进行配对孵育，其中一种或另一种糖用14C标记。当果糖被标记时，释放到培养基中的葡萄糖的比放射性大于6-磷酸葡萄糖的比放射性，但当半乳糖被标记时则不然。此外，培养基中的6-磷酸葡萄糖和葡萄糖在C-1和C-6之间的14C分布方面有所不同。这些结果被解释为肝细胞中的6-磷酸葡萄糖并非以均匀的池存在，而是存在与葡萄糖磷酸化、糖异生和糖原分解相关的亚区室的证据。
