Leptomycin B, Free Acid (Elactocin, Mantuamycin, PD 114720, ATS 1287B, CI-940, CL-1957A, NSC 364372,

Solubility: Soluble in methanol or ethanol. More than 1,000 labs worldwide have purchased Leptomycin B from LC Labs (either directly from us or from our many distributors, many of whom resell under their own labels). Leptomycin B (LepB) is a potent, specific inhibitor of nuclear export signal (NES)-dependent protein export from the nucleus. Fukuda. M., et al. 'CRM1 is responsible for intracellular transport mediated by the nuclear export signal.' Nature 390: 308-311 (1997). The effect of LepB on the CRM1 (exportin 1) NES receptor results from selective alkylation by LepB of a single cysteine residue. Kudo, N., et al. 'Leptomycin B inactivates CRM1/exportin 1 by covalent modification at a cysteine residue in the central conserved region.' Proc. Natl. Acad. Sci. USA 96: 9112-9117 (1999) LepB inhibits the nucleo-cytoplasmic translocation of the HIV Rev protein at nanomolar concentrations. Wolff, B., et al. 'Leptomycin B is an inhibitor of nuclear export: inhibition of nucleo-cytoplasmic translocation of the human immunodeficiency virus type 1 (HIV-1) Rev protein and Rev-dependent mRNA.' Chem Biol. 4: 139-147 (1997). LepB also exhibits potent antitumor activity in vitro and in vivo, and possesses potent antimycotic and antibiotic activity. Tunac, J.B., et al. 'Novel antitumor antibiotics, CI-940 (PD 114,720) and PD 114,721. Taxonomy, fermentation and biological activity.' J. Antibiot. 38: 460-465 (1985). POTENCY: LepB typically exhibits IC50 values in the 1 nM range, depending on the species, cell type, and phenomenon under study. Our LepB is supplied in serum bottles with teflon-lined closures containing a solution in absolute ethanol (a better solvent than methanol/water, see 'Solvent' below). The 100 µg size is supplied as 185 µL of a 1 mM solution (540 µg/mL). The 500 µg size is supplied as 925 µL of a 1 mM solution. The 1 mg size is supplied as 1.85 mL of a 1 mM solution. Larger quantities and higher concentrations are available - please request a quotation.