Supplemental Material

This article contains the following supporting material:

• Figure 1 - The formation of NuSAP-asters is not due to non-specific aggregation, but the result of specific interaction. 1 μM of recombinant NuSAP or a mixture of core histones (Roche) were incubated with 10 μM of soluble tubulin in BrB80 buffer with 1 mM GTP, and ficoll and dextran as crowding reagents. The reaction was incubated at 37°C for 15 min, then fixed and analysed by confocal microscopy. NuSAP generated compact microtubule asters and fibers. In contrast, the core histones cause disorganised aggregation of tubulin. Bar, 10 μm.

• Figure 2 - Impα, Impβ, and Imp7 alone do not stabilise or cross-link microtubules. 15 μM tubulin was incubated in BrB80 buffer with 1 mM GTP, and ficoll and dextran as crowding reagents, and 1 μM NuSAP or 5 μM of the individual importins. The reaction was incubated at 37°C for 15 min before fixation and analysis. NuSAP, but not the individual importins, converted tubulin into small asters and fibers. Bar, 10 μm.