2.1. In silico analysis of the human ABCB10 gene promoter
In order to identify the basic transcriptional regulatory mechanisms
of the ABCB10 gene, we performed a bioinformatic search of the genomic
sequence immediately preceding the start of the protein coding region
for potential promoter elements and regulatory sites. Within the
potential ABCB10 promoter, we were unable to identify any canonical
TATA box sequences. Since it is well documented that most of the
human TATA-less promoters are associated with CpG islands [18,19],
we analysed the 5′-flanking region of ABCB10 using CpG Island Searcher
software, identifying a classical CpG island (at−845/+906 bp), within
the expected location of the ABCB10 core promoter with GC content
above 68%. Analysis of the resources of the Database of Transcriptional
Start Sites (DBTSS) showed that there is no single major TSS (Transcriptional
Start Site), with TSSs identified by large-scale sequencing experiments
dispersed between nucleotides −306 and −53 relative to the
ATG translation initiation codon (Fig. 1). The most prominent concentration
of transcriptional start sites, suggesting the location of core regulatory
sequences, is located within a 100 bp stretch of genomic
sequence between nucleotides −320 and −220.