Control of intracellular pH. Predominant role of oxidative metabolism, not proton transport, in the eukaryotic microorganism Neurospora.
Open Access
- 31 August 1982
- journal article
- research article
- Published by Rockefeller University Press in The Journal of general physiology
- Vol. 80 (3), 377-402
- https://doi.org/10.1085/jgp.80.3.377
Abstract
Recessed-tip microelectrodes were used to measure internal pH (pHi) in the fungus Neurospora, and to examine the response of pHi to several kinds of stress: changes of extracellular pH (pHo), inhibition of the principal proton pump in the plasma membrane, and inhibition of respiration. Under control conditions, at pHo = 5.8, pHi in Neurospora is 7.19 +/- 0.04. Changes of pHo between 3.9 and 9.3 affect pHi linearly but with a slope of only approximately 0.1 unit pHi per unit pHo, stable pHi being reached within 3 min of changed pHo. Despite a postulated high passive permeability of the Neurospora membrane to protons (Slayman, 1970), neither active nor passive H+ transport appears critical to pHi because (alpha) specific inhibition of the proton pump by orthovanadate has little effect on pHi, and (b) cytoplasmic acidification produced by respiratory blockade is unaffected by the size or direction of proton gradient. To convert measured changes in pHi into net proton fluxes, intracellular buffering capacity (beta i) was measured by the weak acid/weak base technique. At pHi = 7.2, beta i was (-) 35 mmol H+ (liter cell water)-1 (pH unit)-1, but beta i increased substantially in both the acid and alkaline directions, which suggests that amino acid side chains are the principal source of buffer.This publication has 15 references indexed in Scilit:
- Phosphorus-31 nuclear magnetic resonance studies of wild-type and glycolytic pathway mutants of Saccharomyces cerevisiaeBiochemistry, 1979
- Membrane H+ conductance of Streptococcus lactisJournal of Bacteriology, 1979
- The effects of vanadate on the plasma membrane ATPase of Neurospora crassa.Journal of Biological Chemistry, 1979
- Current-voltage relationships for the plasma membrane and its principal electrogenic pump inNeurospora crassa: I. Steady-state conditionsThe Journal of Membrane Biology, 1978
- Do light-induced changes in the membrane potential ofNitella reflect the feed-back regulation of a cytoplasmic parameter?The Journal of Membrane Biology, 1978
- 31P nuclear magnetic resonance studies of bioenergetics and glycolysis in anaerobic Escherichia coli cells.Proceedings of the National Academy of Sciences, 1978
- The effect of carbon dioxide on the intracellular pH and buffering power of snail neurones.The Journal of Physiology, 1976
- Electrical Properties of Neurospora crassa The Journal of general physiology, 1965
- Potassium transport in NeurosporaBiochimica et Biophysica Acta (BBA) - Specialized Section on Biophysical Subjects, 1964
- Microelectrode Experiments on NitellaAustralian Journal of Biological Sciences, 1955