Hexose transport derepressed and refractory to purine regulation in NAD(H)-depleted Nil cells
✍ Scribed by Kenneth G. Mandel; Harold Amos
- Publisher
- John Wiley and Sons
- Year
- 1984
- Tongue
- English
- Weight
- 714 KB
- Volume
- 118
- Category
- Article
- ISSN
- 0021-9541
No coin nor oath required. For personal study only.
✦ Synopsis
Nil hamster fibroblasts depleted of NAD(H) by growth in medium devoid of nicotinamide (NAm-MEM) exhibit u p to 2-3-fold higher rates of glucose transport. Derepression of glucose transport is observed only when Nil cells have become severely depleted of both intracellular NAD(H) and ATP, despite the continued presence of 5.5 mM D-glucose in the growth medium. Neither t h e initial rate of transport, approximated from 3-0-methylglucose uptake, nor accumulation of D-glucose itself is repressed upon restoring nicotinamide to the medium. Exposure of the cells to N A D + M), however, leads to a sharp curtailment of transport within 2 to 3 hours. The purines, hypoxanthine and guanine, that sharply reduce glucose transport capacity of normal cells, have no significant effect upon transport activity of NAD(H)-depleted cells.
'The terms "repression" and "' derepression " as used in this manuscript do not imply control at the level of mRNA synthesis. Use is predicated on the requirement for protein synthesis to increase transport in the cells in question.