Proteinaceous Complexes from Mitochondrial Contact Sites

M. Yu. Vyssokikh¹, N. Yu. Goncharova², A. V. Zhuravlyova³, L. D. Zorova¹, V. V. Kirichenko¹, B. F. Krasnikov^1,4, A. E. Kuzminova¹, K. Ch. Melikov⁵, N. S. Melik-Nubarov³, A. V. Samsonov⁵, V. V. Belousov¹, A. E. Prischepova¹, and D. B. Zorov^1*

¹Belozersky Institute Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia; fax: (095) 939-3188; E-mail: zorov@energ.genebee.msu.su

²Department of Biochemistry, School of Biology, Lomonosov Moscow State University, Moscow, Russia

³School of Chemistry, Lomonosov Moscow State University, Moscow, Russia

⁴International Laser Center, Lomonosov Moscow State University, Moscow, Russia

⁵Frumkin Electrochemistry Institute, Russian Academy of Sciences, Moscow, Russia

^* To whom correspondence should be addressed.

Received December 15, 1997; Revision received October 26, 1998

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A Triton X-100 extract from rat brain mitochondria was obtained using low detergent/protein ratio. From this extract a proteinaceous complex was purified; its molecular weight was as high as 880 kD. The complex contained both hexokinase and creatine kinase activity. When incorporated into phospholipid bilayer membranes, the complex formed a channel whose activity was different than the channel activity of purified porin isolated either by adsorption chromatography or by dissociation from protein complexes. A ligand of the mitochondrial benzodiazepine receptor (Ro5-4864) in submicromolar concentrations had an apparent influence on the kinetic behavior of enzymatic coupling of hexokinase and creatine kinase. It is suggested that the 880-kD complex is formed by mitochondrial contact sites. The role of the isolated protein complex in the formation of nonspecific permeability in mitochondria is discussed.

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KEY WORDS: mitochondria, contact sites, hexokinase, creatine kinase, porin, adenine nucleotide transporter, cyclophilin, proteinaceous complex, benzodiazepine receptor, transition pore, nonspecific permeability, regulation

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