Summary
Patch-clamp studies have been employed in order to check whether the assumption of a multi-ion single-file pore is necessary for the explanation of the anomalous mole fraction effect or whether this effect can also be explained by a single-barrier enzyme kinetic model. Experiments in the cell-attached configuration were done on the tonoplast membrane of cytoplasmic droplets ofNitella in solutions containing 150 mol m−3 of K+ plus Tl+ with seven different K+/Tl+ ratios. At first sight, the results seem to support the multi-ion single-file pore, because apparent open channel conductivity displays the anomalous mole fraction effect, whereas open-probability has not been found to be dependent on the K+/Tl+ ratio. Changes in open probability would be expected for a single-barrier enzyme kinetic model with a lazy state. On the other hand, the lazy-state model is more successful in explaining the measuredI-V curves. The entire slope of the apparent open channel current-voltage curves rotates with changing K+/Tl+ ratios in the whole voltage range between −100 and + 80 mV. Numerical calculations on the basis of multi-ion single-file pores could create the anomalous mole fraction effect only in a limited voltage range with intersectingI-V curves. The apparent absence of an effect on open probability which is postulated by the lazy-state model can be explained if switching into and out of the lazy state is faster than can be resolved by the temporal resolution of 1 msec.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Bertl, A. 1989. Current-voltage relationships of a sodium-sensitive potassium channel in the tonoplast ofChara corallina.J. Membrane Biol. 109:9–19
Bertl, A., Gradmann, D. 1987. Current-voltage relationships of potassium channels in the plasmalemma ofAcetabularia.J. Membrane Biol. 99:41–49
Bertl, A., Klieber, H.G., Gradmann, D. 1988. Slow kinetics of a potassium channel inAcetabularia.J. Membrane Biol. 102:141–152
Bezanilla, F. 1985. A high capacity data recording device based on a digital audio processor and a video cassette recorder.Biophys. J. 47:437–441
Blatt, M.R. 1988. Potassium-dependent, bipolar gating of K+ channels in guard cells.J. Membrane Biol. 102, 235–246
Fisahn, J., Hansen, U.-P., Gradmann, D. 1986. Determination of charge, stoichiometry and reaction constants fromI-V curve studies on a K+ transporter inNitella.J. Membrane Biol. 94:245–252
Goodwin, G.C., Sin, K.S. 1984. Adaptive Filtering Prediction and Control. pp. 505–507, Prentice-Hall, Englewood Cliffs
Gradmann, D., Klieber, H.G., Hansen, U.P. 1987. Reaction kinetic parameters for ion transport from steady-state currentvoltage curves.Biophys. J. 51:569–585
Gray, M.A., Greenwell, J.R., Garton, A.J., Argent, B.E. 1990. Regulation of maxi-K+ channels on pancreatic duct cells by cyclic AMP-dependent phosphorylation.J. Membrane Biol. 115:203–215
Hagiwara, S., Miyazaki, S., Krasne, S., Ciani, S. 1977. Anomalous permeabilities of the egg cell membrane of a starfish in K+-Tl+ mixtures.J. Gen. Physiol. 70:269–281
Hansen, U.P. 1990. Implications of control theory for homeostasis and phosphorylation of transport molecules.Bot. Acta 103:15–23
Hansen, U.P., Dau, H., Vanselow K.H., Fisahn, J., Stein, S., Kolbowski, J. 1989. Thylakoid and plasmalemma fluxes.In: Plant Membrane Transport: The Current Position. J. Dainty, M.I. De Michelis, E. Marrè, and F. Rasi-Caldogno, editors. pp. 345–350. Elsevier, Amsterdam-New York-Oxford
Hansen, U.-P., Fisahn, J. 1987.I-V-curve studies of the control of a K+-transporter inNitella by temperature.J. Membrane Biol. 98:1–13
Hansen, U.P., Gradmann, D., Sanders, D., Slayman, C.L. 1981. Interpretations of current-voltage relationships for “active” ion transport systems: I. Steady-state reaction-kinetic analysis of class-I mechanisms.J. Membrane Biol. 63:165–190
Hansen, U.-P., Tittor, J., Gradmann, D. 1983. Interpretation of current-voltage relationships for “active” ion transport systems: II. Nonsteady-state reaction-kinetic analysis of Class-I mechanisms with one slow time-constant.J. Membrane Biol. 75:141–169
Hedrich, R., Schroeder, J.I. 1989. The physiology of ion channels and electrogenic pumps in higher plants.Ann. Rev. Plant Physiol. 40:539–569
Heinemann, S.H., Sigworth, F.J. 1990. Open channel noise: V. Fluctuating barriers to ion entry in gramicidin A channels.Biophys. J. 57:499–514
Hille, B., Schwarz, W. 1978. Potassium channels as multi-ion single-file pores.J. Gen. Physiol. 72:409–442
King, E.L., Altmann, C. 1956. A schematic method of deriving the rate laws for enzyme-catalyzed reactions.J. Phys. Chem. 60:1375–1378
Kolarev, J., Kulpa, J., Baijot, M., Goffeau, A. 1988. Characterization of a protein serine kinase from yeast plasma membrane.J. Biol. Chem. 263:10613–10619
Laver, D.R., Fairley, K.A., Walker, N.A. 1989. Ion permeation in a K+ channel inChara australis: Direct evidence for diffusion limitation of ion flow in a maxi-K channel.J. Membrane Biol. 108:153–164
Lühring, H. 1986. Recording of single K+ channels in the membrane of cytoplasmic drop ofChara australis.Protoplasma 133:19–28
McDonough, J.P., Mahler, H.P. 1982. Covalent phosphorylation of the Mg2+-dependent ATPase of yeast plasma membranes.J. Biol. Chem. 257:14579–14581
Negulyaev, Yu.A., Vedernikova, E.A., Savokhina, G.A. 1990. Aconitine-induced modification of single sodium channels in neuroblastoma cell membrane.Gen. Physiol. Biophys. 9:167–176
Nollau, V. 1979. Statistische Analysen. Birkhäuser, Basel-Stuttgart
Pietrobon, D., Prod'hom, B., Hess, P. 1988. Conformational changes associated with ion permeation in L-type calcium channels.Nature 333:373–376
Portillo, F., Mazon, M.J. 1985. Activation of yeast plasma membrane ATPase by phorbol ester.FEBS Lett. 192:95–98
Prod'hom, B., Pietrobon, D., Hess, P. 1987. Direct measurement of proton transfer rates to a group controlling the dihydropyridine-sensitive Ca2+ channel.Nature 239:243–246
Sachs, L. 1984. Applied Statistics. Springer-Verlag, New York-Berlin-Heidelberg-Tokyo
Sakano, K., Tazawa, M. 1986. Tonoplast origin of the envelope membrane of cytoplasmic droplets prepared fromChara internodal cells.Protoplasma 131:247–249
Sorensen, H.W. 1980. Parameter Estimation. pp. 183–199. Marcel Dekker, New York-Basel
Tester, M. 1988. Potassium channels in the plasmalemma ofChara corallina are multi-ion pores: Voltage-dependent blockade by Cs+ and anomalous permeabilities.J. Membrane Biol. 105:87–94
Tyerman, S.D., Findlay, G.P. 1989. Current-voltage curves of single Cl− channels which coexist with two types of K− channels in the tonoplast ofChara corallina.J. Exp. Bot. 40:105–117
Vanselow, K.H., Hansen, U.P. 1989. The rapid effect of light on the K+ channel inNitella.J. Membrane Biol. 110:175–187
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Draber, S., Schultze, R. & Hansen, UP. Patch-clamp studies on the anomalous mole fraction effect of the K+ channel in cytoplasmic droplets ofNitella: An attempt to distinguish between a multi-ion single-file pore and an enzyme kinetic model with lazy state. J. Membrain Biol. 123, 183–190 (1991). https://doi.org/10.1007/BF01998088
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF01998088