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 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.
Jezek
P
P
Department of Pharmacology, Medical College of Ohio, Toledo, Ohio 43699.
Mahdi
F
F
Garlid
K D
KD
D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000378:metabolism*; D005456:Fluorescent Dyes; D007425:Intracellular Membranes / Q000378:metabolism*; D007700:Kinetics; D008081:Liposomes; D008433:Mathematics; D008929:Mitochondria, Heart / Q000201:enzymology*; D008930:Mitochondria, Liver / Q000201:enzymology*; D011188:Potassium / Q000378:metabolism*; D027961:Potassium-Hydrogen Antiporters; D011510:Proteolipids / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers; D013050:Spectrometry, Fluorescence; D013367:Submitochondrial Particles / Q000378:metabolism*
D002352:Carrier Proteins; D005456:Fluorescent Dyes; D008081:Liposomes; D027961:Potassium-Hydrogen Antiporters; D011510:Proteolipids; D017923:Sodium-Hydrogen Exchangers; C020485:proteoliposomes; D011188:Potassium