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. Author manuscript; available in PMC: 2012 Jul 15.
Published in final edited form as: ACS Chem Biol. 2011 Apr 21;6(7):700–708. doi: 10.1021/cb2000296

Figure 1.

Figure 1

A high-throughput screen identifies importazole as an inhibitor of FRET between CFP-Ran and YFP-importin-β. (a) Schematic of the fusion proteins that bind and undergo FRET in the presence of Ran-GTP but not Ran-GDP. (b) Fluorescence emission of the FRET pair detected between 460 nm and 550 nm following excitation at 435 nm, showing strong emission of CFP (475 nm) in the presence of GDP (red curve) that decreases in the presence of GTP (blue curve) concomitant with an increase at the emission wavelength of YFP (525 nm), indicative of FRET. (c) Summary of the screen. Of 137,284 small molecules screened in duplicate using the FRET-based assay, 141 putative hits were subjected to three secondary screens designed to eliminate false positives. Of the 10 compounds remaining after the secondary screens, only a single compound reproducibly diminished the FRET signal generated by CFP-Ran and YFP-importin-β in the original assay (d). (e) The structure of importazole, a 2,4-diaminoquinazoline.