Document Detail

Properties of a transplasma membrane electron transport system in HeLa cells.
MedLine Citation:
PMID:  6537437     Owner:  NLM     Status:  MEDLINE    
A transmembrane electron transport system has been studied in HeLa cells using an external impermeable oxidant, ferricyanide. Reduction of ferricyanide by HeLa cells shows biphasic kinetics with a rate up to 500 nmoles/min/g w.w. (wet weight) for the fast phase and half of this rate for the slow phase. The apparent Km is 0.125 mM for the fast rate and 0.24 mM for the slow rate. The rate of reduction is proportional to cell concentration. Inhibition of the rate by glycolysis inhibitors indicates the reduction is dependent on glycolysis, which contributes the cytoplasmic electron donor NADH. Ferricyanide reduction is shown to take place on the outside of cells for it is affected by external pH and agents which react with the external surface. Ferricyanide reduction is accompanied by proton release from the cells. For each mole of ferricyanide reduced, 2.3 moles of protons are released. It is, therefore, concluded that a transmembrane redox system in HeLa cells is coupled to proton gradient generation across the membrane. We propose that this redox system may be an energy source for control of membrane function in HeLa cells. The promotion of cell growth by ferricyanide (0.33-0.1 mM), which can partially replace serum as a growth factor, strongly supports this hypothesis.
I L Sun; F L Crane; C Grebing; H Löw
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of bioenergetics and biomembranes     Volume:  16     ISSN:  0145-479X     ISO Abbreviation:  J. Bioenerg. Biomembr.     Publication Date:  1984 Dec 
Date Detail:
Created Date:  1985-09-30     Completed Date:  1985-09-30     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7701859     Medline TA:  J Bioenerg Biomembr     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  583-95     Citation Subset:  IM    
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MeSH Terms
Cell Division
Cell Membrane / metabolism
Electron Transport
Ferricyanides / metabolism*
Glycolysis / drug effects
Hela Cells / metabolism*,  ultrastructure
Hydrogen-Ion Concentration
Membrane Potentials
NAD / metabolism
NADH, NADPH Oxidoreductases / metabolism
Grant Support
K6-21839//PHS HHS
Reg. No./Substance:
0/Ferricyanides; 13408-62-3/hexacyanoferrate III; 53-84-9/NAD; EC 1.6.-/NADH, NADPH Oxidoreductases; EC 1.6.99.-/ferricyanide reductase

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