Tubulin does not bind glycerol irreversibly

Tubulin incorporates radioactivity when incubated with preparations of ¹⁴C]-glycerol, but the material that binds to tubulin is a contaminant rather than glycerol itself. The apparent binding of glycerol by tubulin was not stoichiometric, nor was it significantly affected by dilution of the radioactive glycerol preparation with unlabelled glycerol. Radioactive glycerol purified by prior exposure to protein was an order of magnitude less effective in binding to tubulin than unpurified glycerol. Cytochrome-C and bovine plasma albumin, as well as tubulin, incorporated radioactivity from isotopically labelled glycerol. The amount of radioactivity incorporated into tubulin was unaffected by assembly-disassembly.