Reconstituted adenine nucleotide translocase forms a channel for small molecules comparable to the mitochondrial permeability transition pore.
Highly purified adenylate translocase (ANT) from rat heart mitochondria was functionally reconstituted as ATP/ADP exchange carrier in asolectin/cardiolipin vesicles. The ANT preparations used were free of porin, cyclophilin D, and Bax as analysed immunologically and by activity measurements. After pre-loading the ANT-containing proteoliposomes with ATP, malate or AMP, a gradual release of the trapped compounds by increasing the external Ca2+ concentrations could be demonstrated. N-Methyl-Val-4-cyclosporin did not inhibit the Ca2+ dependent release of internal substances from ANT liposomes. This inhibitor was found to be specific for the mitochondrial permeability transition pore (MTP) in intact mitochondria or reconstituted MTP-like protein complexes (e.g. hexokinase, porin, ANT complex). However, ADP in concentrations > 20 microM inhibited the liberation of internal compounds, while in contrast, atractyloside (30 microM) and HgCl2 (5 microM) both induced permeability of the ANT-containing liposomes resulting in a release of trapped substances. These results strongly suggest that ANT itself is capable to adopt a pore-like structure under conditions known to induce the permeability transition in mitochondria.
Rück
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A
Faculty of Biology, University of Konstanz, Germany.
Dolder
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M
Wallimann
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T
Brdiczka
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D
D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000502:physiology; D002308:Cardiolipins; D007473:Ion Channels / Q000737:chemistry*; D008081:Liposomes; D008929:Mitochondria, Heart / Q000737:chemistry* / Q000378:metabolism; D000226:Mitochondrial ADP, ATP Translocases / Q000737:chemistry*; D008970:Molecular Weight; D010539:Permeability; D010713:Phosphatidylcholines; D010743:Phospholipids; D051381:Rats
D002308:Cardiolipins; D007473:Ion Channels; D008081:Liposomes; D010713:Phosphatidylcholines; D010743:Phospholipids; C024990:asolectin; D000226:Mitochondrial ADP, ATP Translocases; D002118:Calcium