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Recording of single K+ channels in the membrane of cytoplasmic drop ofChara australis

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Summary

The cytoplasmic drop formed of effused cytoplasm fromChara internodes is enclosed by a membrane. Patch clamp experiments have been carried out on this membrane, revealing a K+ channel as the most frequently detected ion translocator. The K+ channel is saturated at a level of about 20 pA inward and 10 pA outward current. The channel conductance is dependent on the accessability of K+ ions, its maximum value amounts to about 165 pS. The discrimination of Na+ and Cl− is significant, permeability ratios PNa/PK and PCl/PK were estimated to be 0.01 either. Binding experiments with the fluorescent probe concanavalin A/FITC suggest that the membrane is derived from the tonoplast.

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Abbreviations

EK :

K+ equilibrium potential

FITC:

fluorescein isothiocyanat

Vm :

membrane voltage

Vpip :

pipette clamp voltage

Vr :

reversal voltage

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  1. Botanisches Institut der Universität, Venusbergweg 22, D-5300, Bonn, Federal Republic of Germany

    H. Lühring

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  1. H. Lühring
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Lühring, H. Recording of single K+ channels in the membrane of cytoplasmic drop ofChara australis . Protoplasma 133, 19–28 (1986). https://doi.org/10.1007/BF01293183

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  • DOI: https://doi.org/10.1007/BF01293183

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