Hemiasterlin is more like dolastatin 10 than cryptophycin 1* (cf. preincubation). Like other vinca domain drugs (e.g., dolastatin 10, cryptophycin 1), hemiasterlin affects the GT/DP exchange; but data not shown and results published elsewhere indicate that these do not bind in that (exchangeable/E-) site.

Though hemiasterlin induces tubulin oligopolymers, consider:

1. There are agents that do not induce tubulin oligopolymers, yet do inhibit (a) vinblastine's binding to tubulin and (b) nucleotide exchange.
2. Vinblastine itself does not inhibit exchange even at concentrations that induce tubulin spirals.

*Cryptophycin 1 a.k.a. cryptophycinA

Details: To drug + 10µM tubulin (0.1 M MES, pH 6.9, 5% DMSO, 0.5 mM MgCl₂) was added 50µM [8-¹⁴C]GTP (always added last). Following a 15 minute incubation, *GTP–tubulin was resolved in duplicate samples by centrifugal gel filtration (Sephadex G-50). Points are means of 3 experiments. All at 4°C.
 

Type a brief message to author (include your e-mail if so desired): Enter your e-mail address: Enter your e-mail address, again: (For more lengthy purposes, use E-Z form or e-mail.)