Specific characteristics of phosphofructokinase‐microtubule interaction

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Abstract
Muscle phosphofructokinase interacts with microtubule-associated protein-free microtubules resulting in a reduction of the overall activity of the enzyme [Lehotzky et al. (1993) J. Biol. Chem. 268,10888–10894] and periodical cross-linking of the tubules [Lehotzky et al. (1994) Biochem. Biophys. Res. Commun. 204, 585–5911. Microtubule polymers of ‘tail-free’ tubulin obtained by removal of the carboxy-termini with limited subtilisin digestion retain the binding domains for phosphofructokinase that cross-bridges microtubule ‘bodies’. Microtubule-associated proteins bound on tubulin ‘tails’ do not perturb the kinase binding. These data suggest that the tubulin carboxy-terminal domain is not involved in microtubule-phosphofructokinase interactions and phosphofructokinase and microtubule-associated proteins have distinct binding domains on microtubules. Of different isoforms of phosphofructokinase, occurring mainly in brain and tumor cells, the muscle isoform exhibits selective adsorption behaviour on microtubules. Phosphofructokinase M and C isoforms with different associative and allosteric properties may represent an auxiliary pathway to modulate energy production via glycolysis.