The transcription start sites of the reverse transcript from BRCA2 gene bi-directional promoter. (A) GeneRacer amplification product for ZAR2. See Materials and methods for details. (B) Nucleotide sequence of human ZAR2/BRCA2 bi-directional promoter. The transcriptional start sites (TSSs), as determined by GeneRacer technique, are shown. The segment in green color is the sequence complementary to part of the intron 1 sequence of human BRCA2 gene, the segment in red color is from exon 1 and the blue part is from the upstream sequence of BRCA2 gene. The E-box sequence essential for BRCA2 gene expression [18, 19] is underlined. The splice donor site at the ZAR2 gene exon 1/intron 1 junction is indicated by a downward arrow. The 'G' residue at the SNP site at -26 from BRCA2 gene transcription start site is shown by a red *. (C) Cartoon showing the human BRCA2 (upper panel) and ZAR2 (lower panel) gene promoter studied. The identities of ZAR2 exon1 (Ex-1) and intron 1 (Int-1) were experimentally determined in this study. TSS: transcription start site (designated as +1); URS: upstream regulatory sequence.