Figure 4

Comparative genomics of 5'UTR introns within non-receptor tyrosine kinases. Several human NRTKs have multiple splice isoforms and for these we used three different methods for calculating total 5'UTR intron length: mean of 5'UTR intron length for isoforms with 5'UTR introns (HS_Mean); longest total 5'UTR intron length (HS_Longest); 5'UTR intron length most similar to its ortholog in the genome of interest (HS_Closest). (a) Heatmap of length correlation (considering genes with non-zero 5'UTR intron lengths) was plotted for the specified comparisons. As expected from the evolutionary distances between the analyzed species, the highest correlation (93%) was observed between mouse and rat NRTKs. (b) For each mouse ortholog of a human NRTK, the heatmap depicts the changes in total 5'UTR intron length (color reflects log₁₀ of total 5'UTR intron length). The histogram above the color scale summarizes the distribution of changes in 5'UTR intron length. A 5'UTR intron may be present in mouse but not in the compared species (light blue) or vice versa (dark blue). Comparisons require an annotated 5'UTR for each ortholog, and were therefore not possible in some cases (white). (c) Same as (b) but substituting 'rat' for 'mouse'. (d) Human genomic region containing the 5'UTR and first few coding exons (UCSC Genome Browser view). '7X Regulatory Potential', for which higher scores indicate a greater potential for harboring regulatory sequence elements, was calculated using alignments of seven mammalian genomes as previously described [44].