Aldolase-tubulin interactions: removal of tubulin C-terminals impairs interactions.

Aldolase copelleted with taxol stabilized microtubules with a Bmax = 0.74 moles of aldolase per mole of tubulin dimer. Removal of the carboxy terminals from microtubules with limited subtilisin digestion, decreased binding to 0.16 moles of aldolase per mole of tubulin dimer. Aldolase inhibited subtilisin cleavage of the C-terminals while triose phosphate isomerase, an enzyme that does not interact with microtubules, did not affect subtilisin activity. These data indicate that the carboxy terminals are involved in tubulin-aldolase interactions.