(A) Constructs containing point mutations in SRE-1 (S1), SRE-2 (S2), or SRE-1 and -2 (S1,2); replacement of the E-box with a scrambled sequence (E) or point mutations in SRE-1, SRE-2, and the mutant E-box (ES1,2) were ligated to a luciferase reporter. Bold underlined letters indicate mutated bases. (B) Left panel: Effect of point mutations in putative SREs and E-box on SREBP-1a–stimulated GIRK1 promoter activity (n = 4; P < 0.01). Right panel: Basal activities of the constructs containing point mutations. n ≥ 5. (C) Effect of point mutations on LPDS stimulation of GIRK1 promoter activity. Data represent the mean of 7 experiments carried out in triplicate; *P < 0.05. (D) SREBP-1a stimulates a construct containing both SREs and the upstream E-box of the GIRK1 promoter. n = 7; ^†P < 0.001. (E) EMSA demonstrating binding of SREBP-1a to SRE-1 and SRE-2 in the GIRK1 promoter as described in Methods. Oligonucleotides containing the SRE site of the LDL receptor promoter were used as a positive control; 1, oligo alone; 2, oligo plus SREBP-1a; 3, oligo plus SREBP-1a plus anti–SREBP-1 antibody. (F) As in D, except binding was to oligos containing either WT or mutant SREs from the GIRK1 promoter. (G) Competition assay for binding of oligos containing point mutations in SRE-1 and SRE-2. Fold excess of the unlabeled competitor is indicated. (H) Quantification of data in G. Data are plotted as the ratio of residual binding to binding in the absence of competitor. n = 4; ^‡P < 0.01. (I) Binding of SREBP-1a to the E-box in the GIRK1 promoter with oligonucleotides containing WT and mutant E-boxes.