FIGURE 2.

Repetitive element distribution, homology, and coding potential of mpiR. (A) Distribution of repetitive elements across a 48-kb mpiR-containing region from mouse shows Exons 1, 3, and 4 are largely composed of single copy sequences. Exon positions are shown above, and gray boxes identify a region within Intron 2 and Exon 3 where the relative spacing of unique (single copy) and repetitive elements is similar between the mouse and rat mpiR genes. (B) BLASTN (top) and cross-species megaBLAST (bottom) searches using an Exon 4 query reveal fragmented matches toward the 3′-end. The organization and spacing of the nine elements are illustrated by the yellow boxes in the center of the diagram. More than 70 partial or complete copies of these modules are present dispersed throughout the mouse genome on at least 16 chromosomes. (C) Intron 2 of mpiR contained a region homologous to sequences from the 3′-UTR of the lin-28 gene and from Intron 6 of three vomeronasal receptor genes. (D) Representative mpiR transcripts show predicted polypeptides no larger than 57 amino acids. (E) Comparison of sequences from the mouse and rat mpiR genes revealed similar sequence homology from flanking regions, from introns, or from exons.