Luciferase reporter assay of the PLP2-(−113C>A) promoter variant. (A) PLP2-luciferase constructs. A nested set of proximal PLP2 promoter fragments of different lengths (−278, −355, −462 bps from the transcription start site) were cloned into a luciferase reporter vector (pGL3). The −113C>A variant was introduced by site-directed mutagenesis and confirmed by sequencing. (B) Expression of the PLP2-luciferase constructs transiently transfected into HEK293 cells. The mean of the luciferase activities from duplicate studies of each construct was calculated after normalization using the expression of a cotransfected beta-galactosidase expression vector. Note the reduced expression of luciferase activity in HEK293 cells transfected with the three constructs carrying the −113C>A SNP as compared to that with the corresponding control constructs.