Figure 2.

Chromosomal location of related NR gene clusters i and ii. Genes are labeled on each figure, and closely related paralogs are similarly shaded. Coordinate positions for each chromosome are indicated below the number lines. Gene arrow lengths are proportional to the size of each gene. (A) Cluster i spans ∼270 kb. The inset gives a scale drawing of the relationship of the NR1A1 and 1D1 genes. The three known variants of NR1A1 are shown. Coding exons are shaded boxes, 3′ UTRs are open. A filled inverted triangle marks the splice acceptor of the invariant LBD splice junction (see also Fig. 3B). (B) Cluster ii, ∼1.4 Mb. The rat gene for NR1D2 is only presumed to exist at the indicated position. Sequences for this gene are absent from the assembly, and a gap exists at this position (indicated by the broken line). The rat NR1B2 is a partial gene, containing a DBD but not an LBD, most likely as a result of incomplete assembly of this draft genome. Note that the 1A and 1D genes are on opposite strands in each cluster, in the same orientation relative to each other; their order changes relative to the 1B gene.