H +-coupled (Na +-independent) proline transport in human intestinal (Caco-2) epithelial cell monolayers

• Published in: FEBS letters Vol. 333; no. 1; pp. 78 - 82
• Main Authors: Thwaites, David T., McEwan, Gordon T.A., Cook, Martin J., Hirst, Barry H., Simmons, Nicholas L.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25.10.1993; Elsevier
• Subjects: Amino acid; Biological and medical sciences; Caco-2 cell; Cell physiology; Fundamental and applied biological sciences. Psychology; H +-coupled transport; Human intestine; Intestinal epithelium; Membrane and intracellular transports; Molecular and cellular biology; Proline transport; Amino acid; Intestinal epithelium; H +-coupled transport; Proline transport; Caco-2 cell; Human intestine; Human; Cell culture; Biological transport; Gut; Electrophysiology; Proline; Ions; Confocal microscopy; Proteins; Absorption; Cell line; Aminoacid; pH; Epithelial cell
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(93)80378-8

Previously, absorption of l-proline across the apical membrane of the intestinal enterocyte has been attributed to transport via the Na +-dependent Imino system. However, net (absorptive) transport of proline across intact Caco-2 cell monolayers was enhanced by acidification of the apical environment, under both Na +-containing and Na +-free conditions. This Na +-independent pH-dependent proline flux was associated with H + flow across the apical membrane as determined by continuous measurement of intracellular pH. H +/proline symport was associated with an inward I sc in voltage-clamped Caco-2 epithelial layers demonstrating the electrogenic nature of this transport process. In conclusion Caco-2 cells possess an apically-localised, Na +-independent, electrogenic H +/imino acid transporter which may play an important role in intestinal proline absorption.