Tissue preference of 3′ UTR shortening/lengthening. (a) A schematic diagram for computing 3′ UTR shortening index (USI). C
is the tag counts of corresponding PA cluster while L
denotes the length of corresponding PA cluster. (b) For each given tissue, the relative expression level (X-axis) and 3′ UTR length (Y-axis) of individual genes were ranked among 13 tissues. Each box in a given 2D plot represents a specific subset of genes grouped by their ranks. The color of each box represents enrichment (Red) or depletion (Blue) of the corresponding gene group. Upper panel: two tissues (skeletal muscle and heart) enriched for genes with lower expression rank and longer 3′ UTR; Middle panel: overrepresentation of genes with higher expression rank and shorter 3′ UTR in adult and fetal brain; Bottom panel, both lowly expressed genes with longer 3′ UTR and highly expressed genes with shorter 3′ UTR are enriched in pancreas and spleen. (c) α-synuclein coding gene SNCA shows higher expression rank and shortened effective 3′ UTR in both adult and fetal brain tissues. Normalized tag number is represented in Y-axis. Known RefSeq transcripts are shown at the bottom.