A new scenario of the origin of eukaryotic cell and multicellularity is presented. A concentric pH-gradient has been shown to exist in the cytosol of eukaryotic cells. The most probable source of such gradient is its self-formation in gradient of electric field between center and periphery of a cell. Theoretical analysis has shown that, for example, a cell of Saccharomyces cerevisiae has enough energy to continuously sustain such gradient of strength about 1.5 kV/cm, the value sufficient for effective isoelectric focusing of cytoplasmic proteins. Focusing of enzymes could highly increase the effectiveness of an otherwise diffusion-limited metabolism of large cells by concentrating enzymes into small and distinct parts of a cytoplasm. By taking away an important physical constraint to the volume of cytoplasm, the intracellular isoelectric focusing enabled evolution of cells 3-4 order of magnitude larger than typical prokaryotic cells. This opened the way for the origin of phagocytosis and lately for the development of different forms of endosymbiosis, some of them resulting in an endosymbiotic origin of mitochondria and plastids. The large volume of a cell-enabled separation of nuclear and cytoplasmic compartments which was a precondition for separation of transcription and translation processes and therefore also for the origin of various RNA-preprocessing mechanisms. The possibility to regulate gene expression by postprocessing RNA and to regulate metabolism by an electrophoretic translocation enzymes between different parts of cytoplasm by changing their isoelectric points opened the way for cell and tissue differentiation and therefore for the origin of complex multicellular organisms.

• MeSH
• biologická evoluce * MeSH
• biologické modely MeSH
• cytoplazma fyziologie   MeSH
• eukaryotické buňky * cytologie   fyziologie   MeSH
• fyziologie buňky MeSH
• isoelektrická fokusace * MeSH
• koncentrace vodíkových iontů MeSH
• proteiny fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• proteiny MeSH

Acidification of the external medium of the yeast Saccharomyces cerevisiae, mainly caused by proton extrusion by plasma membrane H(+)-ATPase, was inhibited to different degrees by D2O, diethylstilbestrol, suloctidil, vanadate, erythrosin B, cupric sulfate and dicyclohexylcarbodiimide. The same pattern of inhibition was found with the uptake of amino acids, adenine, uracil, and phosphate and sulfate anions. An increase of the acidification rate by dioctanoylglycerol also increased the rates of uptake of adenine and of glutamic acid. In contrast, a decrease of the membrane potential at pH 4.5 from a mean of -40 to -20 mV caused by 20 mM KCl had no effect on the transport rates. The ATPase-deficient mutant S. cerevisiae pmal-105 showed a markedly lower uptake of all the above solutes as compared with the wild type, while its membrane potential and delta pH were unchanged. Other types of acidification (spontaneous upon suspension; K+ stimulated) did not affect the secondary uptake systems. A partially competitive inhibition between some individual transport systems was observed, most pronouncedly with adenine as the most avidly transported solute. These observations, together with the earlier results that inhibition of H(+)-ATPase activity affects more the acidic than the basic amino acids and that it is more pronounced at higher pH values and at greater solute concentrations, support the view that it is the protons in or at the membrane, as they are extruded by the ATPase, that govern the rates of uptake by secondary active transport systems in yeast.

• MeSH
• aktivní transport MeSH
• kinetika MeSH
• koncentrace vodíkových iontů MeSH
• membránové potenciály MeSH
• protonové ATPasy antagonisté a inhibitory   metabolismus   MeSH
• Saccharomyces cerevisiae enzymologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• protonové ATPasy MeSH

External pH affects the acidification induced by ethanol. The apparent specific rate of acidification depends on the dissociation properties and production of carbon dioxide, acetic and lactic acid which are intermediates of ethanol oxidation. The organic acids are transported by Nernst-Einstein diffusion. We designed and identified a new and simple mathematical model that allows us to describe the effect of external pH on nonstationary transport of dissociated intermediates of ethanol oxidation.

• MeSH
• acetáty metabolismus   MeSH
• aktivní transport MeSH
• biologické modely MeSH
• Candida metabolismus   MeSH
• draslík metabolismus   MeSH
• ethanol metabolismus   MeSH
• kinetika MeSH
• koncentrace vodíkových iontů MeSH
• kyselina mléčná MeSH
• kyselina octová MeSH
• laktáty metabolismus   MeSH
• oxid uhličitý metabolismus   MeSH
• oxidace-redukce MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• acetáty MeSH
• draslík MeSH
• ethanol MeSH
• kyselina mléčná MeSH
• kyselina octová MeSH
• laktáty MeSH
• oxid uhličitý MeSH

Modulators of purine nucleotide (PN) inhibition of H+ and Cl- transport mediated by the uncoupling protein (UP) of brown adipose tissue (BAT) mitochondria were studied: Alkalinization strongly diminishes GDP inhibition of H+ transport (delta log IC50 = -delta pHout), while more intensive inhibition of Cl- transport is only slightly altered. Higher delta psi decreases GDP inhibition of H+ transport. Mg2+, but not palmitoyl-CoA, decreases PN inhibitory ability. Simulations of conditions similar to those found in BAT cells in the resting state and in the thermogenic state showed that three factors act in concert: pH, Mg2+, and free fatty acids (FFA): (a) with endogenous FFA present and 2 mM ATP and 0.5 mM AMP (pH 7.1), H+ transport was inhibited by 95% in the absence of Mg2+, while by 60% with Mg2+; (b) 0.5 mM ATP and 1 mM AMP, H+ transport was inhibited by 40% without Mg2+ and by 30% with Mg2+. State b thus represents a model thermogenic state, while state a represents a resting state. However, the latter state in vivo must be accomplished either by combustion or FFA or by elimination of Mg2+ to attain a total inhibition of H+ transport (cf. a). The model of UP possessing two independent channels, an H+ channel and a Cl- channel, controlled from a single PN-binding site is supported by independent kinetics by different pH dependence of H+ and Cl- transport, and by a lower sensitivity of H+ transport to PN inhibition.

• MeSH
• chloridy metabolismus   MeSH
• hnědá tuková tkáň účinky léků   metabolismus   MeSH
• hořčík farmakologie   MeSH
• iontové kanály účinky léků   metabolismus   MeSH
• koncentrace vodíkových iontů MeSH
• křečci praví MeSH
• křeček rodu Mesocricetus MeSH
• membránové potenciály MeSH
• membránové proteiny metabolismus   MeSH
• mitochondriální proteiny MeSH
• mitochondrie metabolismus   MeSH
• palmitoylkoenzym A farmakologie   MeSH
• purinové nukleotidy farmakologie   MeSH
• techniky in vitro MeSH
• transportní proteiny * MeSH
• uncoupling protein 1 MeSH
• valinomycin farmakologie   MeSH
• zvířata MeSH
• Check Tag
• křečci praví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chloridy MeSH
• hořčík MeSH
• iontové kanály MeSH
• membránové proteiny MeSH
• mitochondriální proteiny MeSH
• palmitoylkoenzym A MeSH
• purinové nukleotidy MeSH
• transportní proteiny * MeSH
• uncoupling protein 1 MeSH
• valinomycin MeSH