Asn803 is required for amphotericin B-induced CAD repression. (A) Structure of Gal4-CAD. (B) AmB repression of CAD of HIF-1α. The plasmid for Gal4-CAD was cotransfected with a Gal4-luc reporter plasmid into Hep3B cells. After incubation under normoxic (21% O₂, ) or hypoxic (1% O₂, ▪) conditions for 16 hours with sodium deoxycholate or AmB, luciferase activities were measured. (C-D) Requirement of Asn803 in the AmB-induced CAD repression. The plasmid for Gal4-CAD mutant, in which Asn803 was substituted with Ala (N803A) or with Asp (N803D), was cotransfected with a Gal4-luc reporter plasmid. (E) No involvement of Cys800 in the AmB repression. The plasmid for Gal4-CAD mutant having Val800 for Cys800 (C800V) was cotransfected with a Gal4-luc reporter plasmid. Results are quoted as relative values versus the normoxic activity of Gal4-CAD and are the means ± SD of 16 experiments. P values versus the hypoxic control are presented in the figures.