Reconstitution of the beef heart and rat liver mitochondrial K+/H+ (Na+/H+) antiporter. Quantitation of K+ transport with the novel fluorescent probe, PBFI

New indicators for fluorescent measurement of Na+ and K+ ions should prove particularly useful for studies of reconstituted carriers of these ions. We show that PBFI, a K(+)-specific probe, provides a convenient and sensitive assay for the study of K+ uptake mediated by the reconstituted mitochondri...

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Veröffentlicht in:The Journal of biological chemistry 1990-06, Vol.265 (18), p.10522-10526
Hauptverfasser: JEZEK, P, MAHDI, F, GARLID, K. D
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Sprache:eng
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Zusammenfassung:New indicators for fluorescent measurement of Na+ and K+ ions should prove particularly useful for studies of reconstituted carriers of these ions. We show that PBFI, a K(+)-specific probe, provides a convenient and sensitive assay for the study of K+ uptake mediated by the reconstituted mitochondrial K+/H+ (Na+/H+) antiporter. Fluorescent measurements have enabled us for the first time to establish reconstitution of the K+/H+ (Na+/H+) antiporter from beef heart as well as from rat liver mitochondria. This technique has also enabled us to establish that dicyclohexylcarbodiimide is capable of complete inhibition of K+/H+ antiport in the reconstituted system, in accord with findings in intact mitochondria. PBFI fluorescence, which measures net K+ uptake, was essential for this corroboration, since dicyclohexylcarbodiimide is not capable of complete inhibition of 42K+/K+ or 86Rb+/Rb+ exchange, presumably because it acts selectively on proton transport within the carrier.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)86978-2