Membrane potential-dependent conformational changes in mitochondrially bound hexokinase of brain.
Previously characterized monoclonal antibodies (Mabs) were used in a study of Type I hexokinase from rat brain. Based on the relative reactivity of these Mabs with soluble and mitochondrially bound forms, binding to mitochondria was shown to affect specific epitopic regions in both N- and C-terminal halves of the enzyme and to modulate conformational changes induced by binding of the ligands, Glc or ATP. Reactivities with Mabs recognizing epitopes in two defined regions of the N-terminal half and one defined region of the C-terminal half of the mitochondrially bound enzyme were selectively affected by mitochondrial membrane potential, or by addition of oligomycin, carboxyatractyloside, or bongkrekic acid. The Glc-6-P analog, 1 ,5-anhydroglucitol-6-P, was much more effective as a competitive inhibitor against extramitochondrial ATP than against intramitochondrial ATP generated by oxidative phosphorylation. These results provide further insight into the role of hexokinase-mitochondrial interactions in regulation of cerebral glucose metabolism.
Hashimoto
M
M
Department of Biochemistry, Michigan State University, East Lansing 48824-1319, USA.
Wilson
J E
JE
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001921:Brain / Q000201:enzymology* / Q000502:physiology; D000939:Epitopes; D005260:Female; D019298:Glucose-6-Phosphate / Q000378:metabolism; D006593:Hexokinase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D006600:Hexosephosphates / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials; D008928:Mitochondria / Q000201:enzymology* / Q000502:physiology; D000226:Mitochondrial ADP, ATP Translocases / Q000378:metabolism; D010766:Phosphorylation; D011487:Protein Conformation; D051381:Rats; D017207:Rats, Sprague-Dawley; D015003:Yeasts
D000911:Antibodies, Monoclonal; D000939:Epitopes; D006600:Hexosephosphates; C000096:1,5-anhydroglucitol-6-phosphate; D019298:Glucose-6-Phosphate; D000255:Adenosine Triphosphate; D000226:Mitochondrial ADP, ATP Translocases; D006593:Hexokinase