Fig. 3. The N-terminal domain of pEg2 shows much less affinity than the full-length protein for paclitaxel-stabilised microtubules in vitro. Microtubules were polymerised in vitro in the presence of purified bovine brain tubulin (lanes 3 and 4), stabilised with paclitaxel and centrifuged through a glycerol cushion to separate microtubules and microtubule associated protein (pellet, P) from proteins that do not associate to microtubules (supernatant, S). In a control reaction, purified tubulin was replaced by bovine serum albumin (lanes 1 and 2). In the presence of paclitaxel, the ß-tubulin is recovered in the pellet (A and C, lane 4) whereas the bovine serum albumin remains in the supernatant (A and C, lane 1). Purified recombinant pEg2-(His)6 (A and B) or purified recombinant Nt-pEg2-(His)6 (C and D) were also incorporated to the reaction. The pellet (P) and the supernatant (S) were analysed for the presence of recombinant proteins using western blotting with the 1C1 monoclonal antibody (diluted 1:100).