AJP - Regulatory, Integrative and Comparative Physiology, Vol 259, Issue 6 1111-R1116, Copyright © 1990 by American Physiological Society
p-Chloromercurobenzene sulfonate inhibition of active Cl- transport in plasma membrane vesicles from Aplysia gut
G. A. Gerencser
Department of Physiology, College of Medicine, University of Florida, Gainesville 32610.
Both a Cl(+)-stimulated adenosinetriphosphatase (ATPase) activity and an
ATP-dependent Cl- transport process were found in Aplysia foregut
absorptive cell plasma membranes. In an attempt to further characterize
this transport process, plasma membrane vesicles from Aplysia foregut
absorptive cells were prepared utilizing differential centrifugation and
sucrose density-gradient techniques. Sulfhydryl ligand participation in
ATP-dependent Cl- transport was confirmed in three ways. First,
1,4-dithiothreitol partially restored a p-chloromercurobenzene sulfonate
(PCMBS)-inhibited ATP-dependent Cl- transport. Second, 1,4-dithiothreitol
restored intravesicular negativity inhibited by PCMBS. Third,
1,4-dithiothreitol had no effect on either ATP-dependent Cl- transport or
ATP-dependent intravesicular negativity inhibited by N-ethylmaleimide.
These results are consistent with the hypothesis that surface sulfhydryl
groups participate in the functioning of the active electrogenic Cl-
transport mechanism in Aplysia gut.
