Dithiols and monothiols are linked with GABA transport in membrane vesicles of rat brain synaptosomes

• Published in: FEBS letters 1987-11, Vol.224 (2), p.391-395
• Main Authors: Robillard, G.T., Schaaf, J.M., Teelken, A.W.
• Format: Article
• Language: English
• Subjects: Animals; Biological Transport - drug effects; brain; Carrier Proteins; GABA Plasma Membrane Transport Proteins; GABA, γ-aminobutyric acid; gamma -aminobutyric acid; gamma-Aminobutyric Acid - metabolism; Kinetics; Male; Membrane Proteins; Membrane Transport Proteins; N-Ethylmaleimide; NEM, N-ethylmaleimide; Nerve Tissue Proteins - metabolism; Neurotransmitter; Organic Anion Transporters; PCMBS, p-chloromercuribenzenesulfonate; Phenylarsine oxide; Rats; Sulfhydryl Compounds; Sulfhydryl reagent; Sulfhydryl Reagents - pharmacology; Synaptosomes - metabolism; Thorin, 4-(2-arsonophenyl)azo-3-hydroxy-2,7-naphthalenedisulfonic acid; γ-Aminobutyric acid
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(87)80490-8

The properties of γ-aminobutyric acid (GABA) transport into membrane vesicles derived from synaptosomes of rat brain have been studied using membrane-permeable and -impermeable sulfhydryl reagents, dithiol-specific reagents and oxidizing reagents. GABA transport is inhibited, reversibly, by very low concentrations of the membrane-permeable trivalent arsenical, phenylarsine oxide. Preincubation with this reagent only partially protects GABA transport from inactivation by N-ethylmaleimide (NEM). Thorin, a negatively charged trivalent arsenical, has no influence on GABA transport at concentrations 100-fold higher than that of the inhibitory phenylarsine oxide. The impermeant oxidizing agent, potassium ferricyanide, did not inhibit transport whereas the permeant reagent, diamide, was inhibitory. These data indicate that the GABA transporter possesses an activity-linked dithiol in a hydrophobic region of the carrier not accessible to charged, polar reagents. p-Chloromercuribenzenesulfonate (PCMBS) also inhibits but does not protect against NEM inactivation, suggesting the occurrence of an activity-linked monothiol in a polar region of the carrier.