High-throughput mapping of the promoters of the mouse olfactory receptor genes reveals a new type of mammalian promoter and provides insight into olfactory receptor gene regulation

Promoters of ORs and other plastic gene families are extremely AT-rich. (A) Olfactory receptor TSS's were mapped, and the %GC distribution of OR (red) and non-OR (gray) promoters (−750 bp to +250 bp relative to TSS) was compared. (B) %GC around the TSS was plotted for ORs (red) and non-ORs sorted by average GC content (orange, black). (C) Promoters ≤40% GC (red) or ≥65% GC (blue) were categorized by gene function (skewing of each category into AT or GC significant, p < 10⁻¹⁰, χ²) (see Methods). (D) Full GC content distribution of averaged biased functional groups (for statistics, see Supplemental Fig. S2; Supplemental Table 1).