GSBS Student Publications

Title

Direct evidence for ATP modulation of sugar transport in human erythrocyte ghosts

GSBS Program

Biochemistry & Molecular Pharmacology

UMMS Affiliation

Graduate School of Biomedical Sciences; Department of Biochemistry and Molecular Pharmacology

Date

8-5-1986

Document Type

Article

Medical Subject Headings

Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Apyrase; Biological Transport; Blood Glucose; Calcium; Cytochalasin B; Erythrocyte Membrane; Humans; Kinetics; Magnesium

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

Sugar transport in human erythrocyte ghosts is modulated by low molecular weight factors present in red cell cytosol that induce an asymmetry in Michaelis and velocity constants for sugar entry and exit (Carruthers, A., and Melchior, D. L. (1983) Biochim. Biophys. Acta 728, 254-266). This study examines the possibility that ATP is the transport-modulating factor. The intracellular factor must satisfy at least three criteria. It must reduce Km and Vmax for sugar efflux from inside-out red cell membrane vesicles. It should increase Km for efflux from red cell ghosts. It should have a molecular weight of less than 10 kDa. These criteria are satisfied by ATP. AMP, ADP, GTP, UTP, and ITP are without effect on sugar transport. The following results support the view that the cytosolic factor is ATP. Red cell lysate (obtained by hypotonic lysis of red cells) is unable to modify transport following dialysis against ATP-free medium. The ability of lysate to modify transport is retained following acid extraction. ATP depletion of acid-extracted lysate by treatment with apyrase results in the loss of transport-modulating potency. Myokinase partly restores both the ATP content and the ability of ATP-depleted (apyrase-treated) lysate to modify transport. Addition of ATP to ATP-depleted lysate mimics the ability to myokinase to restore the transport-modulating potency of lysate. ATP is without effect on the number and molecular size of D-glucose-sensitive cytochalasin B-binding proteins in the red cell membrane. These findings demonstrate that the transport-modulating potency of red cell cytosol is quantitatively accounted for by intracellular ATP which acts to modify the catalytic activity of plasmalemmal transporters.

Rights and Permissions

Citation: J Biol Chem. 1986 Aug 5;261(22):10093-9.

Related Resources

Link to article in PubMed

Journal Title

The Journal of biological chemistry

PubMed ID

3733703