FIG. 1.

Representative immunoblots are presented for kinesin motors and NF proteins in P3 pellets (left panel) and respective S3 supernatants (right panel) of control microtubule preparations. AMPPNP and ATP refer to the different protocols used for preparation of these fractions (see “Materials and Methods” section). Proteins were loaded on gels at 5–10 μg per lane. Respective MWs for individual proteins or peptides are presented to the right of the immunoblots. Relative to corresponding immunoblots from AMPPNP pellets, the reductions in KIF3 and KIF5 band densities in the ATP protocol indicate that these motor proteins were sensitive to ATP-induced release from microtubule binding. Upon release, the subsequently soluble KIF3 and KIF5 appear in the S3 supernatant, as evidenced by the corresponding increase in band densities, that is, compare ATP-derived data for pellet and supernatant. This study also demonstrates that the NF triplet proteins in the P3 pellet did not exhibit ATP sensitivity.