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ATP-dependent sugar transport complexity in human erythrocytes
Jeffry M Leitch1, Anthony Carruthers
1Dept. of Biochemistry and Molecular Pharmacology, Univ. of Massachusetts Medical School, 364 Plantation St., Worcester, MA 01605, USA.
American Journal of Physiology. Cell Physiology
|August 25, 2006
Summary
ATP presence causes biphasic glucose sugar transport in human red blood cells. This phenomenon is attributed to the differential transport of 3-O-methylglucose (3MG) anomers, not cellular heterogeneity or binding.
Area of Science:
- Biochemistry
- Cell Biology
- Physiology
Background:
- Human erythrocyte glucose transport is crucial for cellular energy metabolism.
- The glucose transporter protein (GLUT1) facilitates the movement of glucose across the cell membrane.
- Cytoplasmic ATP levels can influence various cellular transport mechanisms.
Purpose of the Study:
- To investigate the mechanism of biphasic 3-O-methylglucose (3MG) transport in human red blood cells.
- To determine the role of cytoplasmic ATP in regulating glucose sugar transport kinetics.
- To elucidate the underlying cause of the observed biphasic transport phenomenon.
Main Methods:
- Resealed red cell ghosts were used to study equilibrium exchange conditions.
- 3-O-methylglucose (3MG) and uridine transport were measured with and without cytoplasmic ATP.
- Immunofluorescence-activated cell sorting (FACS) was employed to assess cell size and GLUT1 content heterogeneity.
Main Results:
- 3MG exchange transport exhibited monophasic kinetics without ATP but became biphasic in its presence.
- Biphasic transport involved a rapid influx into 66% of cell volume, followed by slower equilibration.
- ATP-dependent differential transport of 3MG anomers (beta-3MG vs. alpha-3MG) was identified as the cause of biphasic kinetics.
Conclusions:
- Biphasic 3MG transport in erythrocytes is an ATP-dependent process.
- The phenomenon is explained by the differential transport rates of 3MG anomers, not by cellular heterogeneity or binding.
- This finding provides new insights into the regulation of glucose transport by intracellular ATP.
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