Transcriptome-sequencing based “virtual Northern” validation of long 3′-UTR expression. (A,B) Peak expression for most transcripts was detected within the size fraction corresponding to the canonical (Ensembl v55) transcript. (A) Graph of canonical transcript size against proportion of transcripts in each fraction. The percentage of transcripts in each bin is shown for each of the five size fractions (0–0.5 kb, 0.5–2 kb, 2–3.5 kb, 3.5–6.5 kb, and 6.5 kb+). (B) Distribution of peak gene expression relative to the expected (Ensembl canonical) size fraction. For example, if peak expression of a 2.5-kb gene was detected in the 6.5-kb+ size fraction, it would be assigned a relative value of 3. (C) Expression levels of individual genes across size fractions. Examples are shown of long 3′-UTR-containing genes (HELLS, GRPR, and POU2F1), a gene containing an extended internal exon (PHF10), and an intron-retaining gene (OGT), genes for which peak expression was detected in the fraction consistent with increased size. POU5F1 (no change expected) is shown for comparison.
