Glutathione transport by inside-out vesicles from human erythrocytes.

AUTOR(ES)

Kondo, T

RESUMO

Purified inside-out vesicles from human erythrocytes were used to investigate the active transport of oxidized glutathione (GSSG). Incubation of vesicles and GSSG in the presence of ATP resulted in the transport of GSSG into the vesicles. When vesicles were incubated with reduced glutathione (GSH), no transport was observed. At GSSG concentrations of less than 5 mM, transport was linear up to 4 hr at 37 degrees C. A Lineweaver-Burk plot of the transport rate as a function of GSSG concentration was biphasic and gave apparent Km values of 0.1 and 7.1 mM. The Km for ATP . Mg in this transport process was 0.63 mM at a GSSG concentration of 20 microM and 1.25 mM at a GSSG concentration of 5 mM. The transport rate at low GSSG concentrations was inhibited by CTP or UTP, which acted as competitive inhibitors of ATP; Ki=0.51 mM. This inhibition may account for the high erythrocyte GSH levels observed in pyrimidine-5'-nucleotidase deficiency, a disorder in which erythrocytic levels of CTP and UTP are elevated.

Documentos Relacionados

• Photosynthetic electron transport from water to NADP+ driven by photosystem II in inside-out chloroplast vesicles
• Bacteriorhodopsin is an inside-out protein.
• Volume-sensitive K-Cl cotransport in inside-out vesicles made from erythrocyte membranes from sheep of low-K phenotype.
• COMBINED INSIDE-OUT AND ALL-INSIDE TECHNIQUE IN BUCKET-HANDLE MENISCUS TEARS
• Cytoplasmic RNA modulators of an inside-out signal-transduction cascade