Reexamination of glucose-6-phosphatase activity in the brain in vivo: no evidence for a futile cycle.
نویسندگان
چکیده
Glucose-6-phosphatase activity in the rat brain in vivo was estimated by measuring the differential loss of tritium and carbon-14 from the glucose pool labeled by a mixture of [2-3H]glucose and [U-14C]glucose. The results provide no evidence of significant dephosphorylation of glucose-6-phosphate and do not support the hypothesis of a futile cycle involving glucose-6-phosphatase activity in the brain.
منابع مشابه
Over-estimation of Glucose-6-phosphatase Activity in Brain in Vivo APPARENT DIFFERENCE IN RATES OF [2-3H]GLUCOSE AND [U-'4C]GLUCOSE UTILIZATION IS DUE TO CONTAMINATION OF PRECURSOR POOL WITH 14C-LABELED PRODUCTS AND INCOMPLETE RECOVERY OF 14C-LABELED METABOLITES*
Significant dephosphorylation of glucose 6-phosphate due to glucose-6-phosphatase activity in rat brain in vivo was recently reported (Huang, M., and Veech, R. L. (1982) J. Biol. Chem. 257, 1135811363). The evidence was an apparent more rapid 3H than '"C loss from the glucose pool and faster [2-3H] glucose than [U-'"C]glucose utilization following pulse labeling of the brain with [2-SH...
متن کاملA New Substrate Cycle in Plants. Evidence for a High Glucose-Phosphate-to-Glucose Turnover from in Vivo Steady-State and Pulse-Labeling Experiments with [C]Glucose and [C]Glucose
Substrate (futile) cycling involving carbohydrate turnover has been widely reported in plant tissues, although its extent, mechanisms, and functions are not well known. In this study, two complementary approaches, short and steady-state labeling experiments, were used to analyze glucose metabolism in maize (Zea mays) root tips. Unidirectional rates of synthesis for storage compounds (starch, Su...
متن کاملA new substrate cycle in plants. Evidence for a high glucose-phosphate-to-glucose turnover from in vivo steady-state and pulse-labeling experiments with [13C]glucose and [14C]glucose.
Substrate (futile) cycling involving carbohydrate turnover has been widely reported in plant tissues, although its extent, mechanisms, and functions are not well known. In this study, two complementary approaches, short and steady-state labeling experiments, were used to analyze glucose metabolism in maize (Zea mays) root tips. Unidirectional rates of synthesis for storage compounds (starch, Su...
متن کاملImpact of Ionizing Radiation on the Expression of CDC25A Phosphatase (in vivo)
Background and Objective: The cell division cycle 25 (CDC25)is a familyof highly conserved dual-specificity phosphatases that activate cyclin-dependent kinase complexes. These complexes are the main cell cycle regulators. Mammalian cells ,exposure to DNA damaging radiations such as ionizing radiation and ultraviolet light, prevent cell cycle progression by activation of checkpoint pathways an...
متن کاملApparent Difference in Rates of [2-3h]glucose and [u-14c]glucose Utilization Is Due to Contamination of Precursor Pool with I4c-labeled Products and Incomplete Recovery of 14c-labeled Metabolites*
Significant dephosphorylation of glucose 6-phosphate due to glucose-6-phosphatase activity in rat brain in vivo was recently reported (Huang, M., and Veech, R. L. (1982) J. Biol. Chem. 257, 1135811363). The evidence was an apparent more rapid 3H than 14C loss from the glucose pool and faster [2-3H] glucose than [U-14C]glucose utilization following pulse labeling of the brain with [2-3H,U-14C]gl...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Science
دوره 229 4708 شماره
صفحات -
تاریخ انتشار 1985