In vitro complex formation between the octamer of mitochondrial creatine kinase and porin.
An interaction of mitochondrial creatine kinase with purified outer mitochondrial porin (voltage-dependent anion channel) was shown by co-sedimentation assays as well as by gel permeation chromatography. Porin formed high M(r) complexes with wild-type mitochondrial creatine kinase as well as with an N-terminal deletion mutant, lacking the first five N-terminal amino acids. The complexes were identified by creatine kinase activity in parallel with immunoblotting using specific antibodies against the two proteins. In addition, porin induced octamerization of the N-terminal creatine kinase mutant, which under the same conditions without porin, did not polymerize but remained more than 90% dimeric. Furthermore, binding of mitochondrial creatine kinase to porin affected the conductance of porin when reconstituted in "black membranes." At 10 mV the pore in the complex adopted a low conductance (1.5-2 nanosiemens) state, compared to the high conductance state (3-4 nanosiemens) of the free incorporated pores. The former state of the pore is known to be cationically selective. Thus, besides a specific structural interaction, a defined physiological function is assumed of the mitochondrial creatine kinase-porin complexes that are discussed here.
Brdiczka
D
D
Faculty of Biology, University of Konstanz, Germany.
Kaldis
P
P
Wallimann
T
T
D000818:Animals; D003402:Creatine Kinase / Q000737:chemistry*; D004553:Electric Conductivity; D066298:In Vitro Techniques; D007473:Ion Channels / Q000737:chemistry*; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000737:chemistry*; D008928:Mitochondria / Q000201:enzymology*; D018272:Porins; D011485:Protein Binding; D051381:Rats; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D050994:Voltage-Dependent Anion Channels
D007473:Ion Channels; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D008565:Membrane Proteins; D018272:Porins; D050994:Voltage-Dependent Anion Channels; D003402:Creatine Kinase