DCCD-sensitive, Na+-dependent H+-influx process coupled to membrane potential formation in membrane vesicles of Halobacterium halobium.
The effects of N,N'-dicyclohexylcarbodiimide (DCCD) on light-induced H+-transport and transmembrane electric potential (delta phi) formation were studied in the membrane vesicles of Halobacterium halobium R1M1. In accordance with our previous finding of the existence of two DCCD-binding components in vesicle membrane using 14C-DCCD (Konishi & Murakami FEBS Lett. 169, 283-286 (1984)), DCCD inhibited the H+-influx process biphasically; that is, the H+-influx process which is electrically silent was initially inhibited at concentrations below 30 nmol of DCCD/mg vesicle protein, while another H+-influx process which is coupled to delta phi formation was secondarily inhibited above this concentration of DCCD. The latter H+-influx process was highly dependent on the Na+ concentration. The extents of Na+-dependent recovery of delta phi formation and H+-influx were quantitatively correlated. From these results, it was concluded that the second DCCD-sensitive H+-influx process which is coupled to delta phi formation is due to the hypothetical Na+/H+-antiporter postulated by Lanyi and MacDonald (Biochemistry 15, 4608-4614 (1976)). It was also found that Li+ can be substituted for Na+ in this system, as is the case with Na+/H+-antiporters found in other organisms.
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Murakami
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Konishi
D002352:Carrier Proteins / Q000378:metabolism*; D002474:Cell-Free System; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology; D006217:Halobacterium / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D007473:Ion Channels / Q000187:drug effects; D008094:Lithium / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009947:Organotin Compounds / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers
D002352:Carrier Proteins; D007473:Ion Channels; D009947:Organotin Compounds; D017923:Sodium-Hydrogen Exchangers; D004024:Dicyclohexylcarbodiimide; D008094:Lithium; D012964:Sodium; C012594:triphenyltin chloride