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Tetrameric structure of mitochondrially bound rat brain hexokinase: a crosslinking study
1Department of Biochemistry, Michigan State University, East Lansing 48824.
Archives of Biochemistry and Biophysics
|January 1, 1990
Summary
Rat brain hexokinase forms tetramers upon binding to mitochondria. This tetramer formation, enhanced by mitochondrial binding, suggests a role in linking hexokinase activity with oxidative phosphorylation via adenine nucleotides.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Hexokinase (EC 2.7.1.1) is a key enzyme in glucose metabolism.
- Its interaction with mitochondria is crucial for regulating cellular energy production.
Purpose of the Study:
- To investigate the quaternary structure of rat brain hexokinase.
- To determine if mitochondrial binding influences hexokinase oligomerization.
Main Methods:
- Derivatization of hexokinase with a photosensitive crosslinking agent (SAND).
- Photolysis of derivatized hexokinase in solution and when bound to liver mitochondria.
- Analysis of crosslinked species using gel electrophoresis.
Main Results:
- Crosslinking revealed a predominant 460 kDa species, identified as a hexokinase tetramer.
- Tetramer formation was significantly enhanced when hexokinase was bound to mitochondria.
- No dimeric or trimeric forms were observed under tested conditions.
Conclusions:
- Hexokinase tetramerization is closely associated with its binding to the outer mitochondrial membrane.
- This oligomerization may occur at mitochondrial pores, facilitating metabolic crosstalk.
- A tetrameric structure could link hexokinase activity to oxidative phosphorylation through adenine nucleotide intermediates.