Using a tensed muscle fiber preparation, we determined the activity of mitochondrially bound hexokinase in rat fast-twitch muscle under control conditions and after low-frequency stimulation periods for up to 2 h. As compared to soluble hexokinase, mitochondrial binding led to stimulation of glucose 6-phosphate production. Low-frequency stimulation greatly enhanced glucose 6-phosphate formation which was 100% and 250% elevated after 1 and 2 h, respectively. These observations point to a mechanism which rapidly increases the catalytic activity of hexokinase through binding to the mitochondrial surface.
Parra, J., Brdiczka, D., Cusso, R., & Pette, D. (1997). Enhanced catalytic activity of hexokinase by work-induced mitochondrial binding in fast-twitch muscle of rat. FEBS Letters, 403(3), 279–282. https://doi.org/10.1016/S0014-5793(97)00047-1