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Dithiols and monothiols are linked with GABA transport in membrane vesicles of rat brain synaptosomes
Author(s) -
Robillard G.T.,
Schaaf J.M.,
Teelken A.W.
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)80490-8
Subject(s) - phenylarsine oxide , reagent , chemistry , vesicle , dithiol , membrane , oxidizing agent , biophysics , biochemistry , membrane potential , biology , enzyme , organic chemistry
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.