FIG. 4.

MP binds saturably to dynamically stabilized microtubules in vitro. Paclitaxel-stabilized microtubules were polymerized in vitro and incubated with increasing amounts of MP-H₆. Microtubule-associated MP (Pellet) and unbound protein (Supernatant) were separated by centrifugation and analyzed by SDS-PAGE and Coomassie blue staining. (A) Saturation binding of purified MP-H₆ in the absence of microtubule polymerization dynamics. (B) Analysis of MP-microtubule binding parameters shows that MP binds microtubules with a relative affinity comparable to structural MAPs. (C) Fluorescence microscopy of the pellet fraction stained for MP and α-tubulin confirms that precipitated MP-H₆ is microtubule associated. (D to F) Polyhistidine does not effect the spread of TMV-MP-GFP and the subcellular distribution of MP-GFP during infection in N. benthamiana leaf epidermis. Bar, 10 μm.