PLANT PHYSIOLOGY , Vol 105, Issue 3 921-926, Copyright © 1994 by American Society of Plant Biologists
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CELL BIOLOGY AND SIGNAL TRANSDUCTION |
Putrescine Channels in the Plasma Membrane of Arabidopsis thaliana
L. Giromini, A. Paina, R. Cerana and R. Colombo
Dipartimento di Biologia, Universita degli Studi di Milano, via Celoria, 26, I-20133 Milano, Italy
The patch-clamp technique was used in the whole-cell configuration to study
plasma membrane channels permeable to the diamine putrescine in protoplasts
isolated from cultured cells of Arabidopsis thaliana L. Under our
experimental conditions, no channels selectively mediating putrescine
influx were observed. Inward K+ channels showed a low permeability to
putrescine, the permeability ratio of putrescine relative to K+ being
around 0.1. Further characterization of the previously identified outward
channels mediating putrescine efflux (R. Colombo, R. Cerana, N. Bagni
[1992] Biochem Biophys Res Commun 182: 1187-1192) indicated that their
activity was regulated by the overall ion concentration of the external
medium.