H+/glycyl-l-proline cotransport in brush border membrane vesicles
of eel (anguilla anguilla) intestine.
Maffia, Michele, Tiziano Verri, Antonio Danieli, Manikkavasagar
Thamotharan, Michele Pastore, Gregory A. Ahearn, and Carlo Storelli.
Laboratorio di Fisiologia Generale, Dipartimento di Biologia,
Universit[grave]a di Lecce, 73100 Lecce, Italy, Department of
Zoology, University of Hawaii at Manoa, Honolulu, Hawaii 96822,
U.S.A., Istituto Sperimentale Talassografico "A. Cerruti", C.
N. R. 74100 Taranto, Italy, Clinical Nutrition Research Unit,
Department of Medicine, University of Pittsburgh, School of Medicine,
Pittsburgh, Pennsylvania 15213, U.S.A.
APStracts 3:0229R, 1996.
A plasma membrane H+/glycyl-L-proline cotransport mechanism has been
identified in isolated eel intestinal brush border membrane vesicles
by both measuring radiolabelled glycyl-L-proline uptake and
monitoring glycyl-L-proline-dependent H+ influx with the pH-sensitive
dye acridine orange. The application of an inside negative membrane
potential resulted in increasing glycyl-L-proline uptake, as well as
the application of inwardly directed H+ gradient (although only when
an inside negative membrane potential was present). Furthermore,
vesicular H+ influx was found specifically associated with the
presence of glycyl-L-proline in the extravesicular medium. The
carrier-mediated nature of H+/glycyl-L-proline cotransport was
assessed and its Kmapp was about 1.30 mM when measured by either
radioactive or fluorescent tracers. Different dipeptides strongly
inhibited glycyl-L-proline uptake by eel intestinal brush border
membrane vesicles, as well as the cephalosporin antibiotic,
cephalexin, suggesting that dipeptide molecules and cephalosporin
antibiotics may share a common transport system in eel intestinal
brush border membrane vesicles.
Received 5 February 1996; accepted in final form 3 June 1996.
APS Manuscript Number R73-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 June 96