Two related compounds, 1,8-anilinonaphthalenesulfonate (1,8-ANS) and bis(1,8-anilinonaphthalenesulfonate) (Bis-ANS), are useful fluorescent probes for hydrophobic areas on protein molecules. Using fluorescence, we examined the binding of these compounds to bovine brain tubulin and found that Bis-ANS and 1,8-ANS bound to tubulin with K(i) values of 2 and 25 μM, respectively. Bis-ANS potently inhibited the polymerization of tubulin into microtubules in vitro. In the presence of microtubule-associated protein 2, half-maximal inhibition of assembly was obtained at 3 μM Bis-ANS. In the presence of tau protein, half-maximal inhibition was obtained at 15 μM Bis-ANS. Surprisingly, 1,8-ANS, even at 200 μM, did not inhibit assembly. Scatchard analysis indicated one binding site for Bis-ANS on tubulin. Previously reports of 1,8-ANS binding to tubulin may have been influenced by the presence of Bis-ANS which until recently was a common contaminant of commercial supplies. Because of its intense fluorescence in addition to its potent inhibitory effects, Bis-ANS appears to be a useful probe to study microtubule assembly and other interactions involving tubulin.
|Original language||English (US)|
|Number of pages||4|
|Journal||Journal of Biological Chemistry|
|State||Published - 1984|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology