Fig. 2.

The J element is the most highly conserved element among OR enhancers. a Nucleotide percent identity plot (VISTA plot) of the junctional region of α- and β-class I OR genes in mouse and human. A 1.9-kb intergenic region, named the J element, was identified as a highly conserved region. b Genomic organization of α-, β-class I OR genes and of the J element in placental mammalian species as a representative of each order. Class I OR genes belonging to different OGGs are depicted by arrowheads of different colors (intact genes, filled; pseudogenes, outlined)⁵. The transcriptional orientation of each OR gene is indicated by the orientation of its arrowhead