Transcription initiation sites and promoter structure of the mouse type 2 inositol 1,4,5-trisphosphate receptor gene.

Transcription initiation sites and the promoter sequence of the ubiquitously expressed mouse type 2 inositol 1,4,5-trisphosphate receptor (IP3R2) gene were determined. In contrast to the nervous system-enriched IP3R1, the IP3R2 gene had multiple (seven major) transcription initiation sites located 334 to 269 bp upstream from the first ATG codon. Transient luciferase assay revealed promoter activity of the IP3R2 sequence upstream from the transcription initiation sites. The IP3R2 promoter was GC-rich and had no conventional TATA box, but had a GC box in the proximal promoter. Multiple transcription start sites were flanked by CpG islands, and various cis elements were located in the promoter. These structural features are considered to be responsible for a profile of IP3R2 gene expression.