PMID: 2782Dec 4, 1975

Analog circuit of the Acetabularia membrane

The Journal of Membrane Biology
D Gradmann


The high membrane potential of Acetabularia (Em=-170mV) is due to an electrogenic pump in parallel with the passive diffusion system (Ed=-80mV) which could be studied separately in the cold, when the pump is blocked. Electrical measurements under normal conditions show that the pump pathway consists of its electromotive force Ep with two elements P1 and P2 in series; P2 is shunted by a large capacitance (Cp=3mF cm-2). The nonlinear current-voltage relationship of P1 (light- and temperature-sensitive) could be determined separately; it reflects the properties of a carrier-mediated electrogenic pump. The value of Ep(-190 mV) indicates a stoichiometry of 2:1 between electrogenically transported charges and ATP. The electrical energy normally stored in Cp, compares well with the metabolic energy, stored in the ATP pool. The nonlinear current-voltage relationship of P2 (attributed to phosphorylating reactions) is also sensitive to light and temperature and is responsible for the region of negative conductance of the overall current-voltage relationship. The power of the pump (1 muW cm-2) amounts to some percent of the total energy turnover. The high Cl- fluxes (1 nmol cm-2 sec-1) and the electrical properties of the plasmalemma are ...Continue Reading


Sep 7, 1976·Biochimica Et Biophysica Acta·H Mummert, D Gradmann
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Jan 1, 1970·Die Naturwissenschaften·D Gradmann, F W Bentrup
Jun 1, 1970·The Journal of General Physiology·H D Saddler
Jul 1, 1970·The Journal of Physiology·R H AdrianA L Hodgkin
Jan 12, 1971·Biochimica Et Biophysica Acta·R M Lilley, A B Hope
Apr 29, 1968·Biochimica Et Biophysica Acta·J HoggR J Johnston
Nov 5, 1968·Biochimica Et Biophysica Acta·W J Cram
Jul 1, 1961·The Journal of General Physiology·K S COLE
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Jun 1, 1983·Plant Cell Reports·V Goldfarb, D Gradmann
Dec 1, 1988·Planta·R BenzU Zimmermann
Oct 20, 1976·The Journal of Membrane Biology·D Gradmann
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Jul 6, 2000·Journal of Photochemistry and Photobiology. B, Biology·M W HoA Scordino
Jan 1, 1989·Annals of the New York Academy of Sciences·D Gradmann
Feb 22, 2005·The New Phytologist·Duc A NgoDina F Mandoli
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Apr 4, 1979·Biochimica Et Biophysica Acta·C Freudling, D Gradmann
Dec 1, 1982·Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences·D GradmannV Goldfarb
Jul 15, 1980·The Journal of Membrane Biology·U KishimotoY Takeuchi
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