Fig. 3
From: Splicing-accessible coding 3′UTRs control protein stability and interaction networks
Translated frameshift-isoforms display an increased proline content resulting in reduced protein stability. a Boxplot comparing the AA content between frameshift and full-length sequences (gray boxes) and between the sequences 100 AA before (CDS) and after canonical stop codons (UTR, white boxes, see Experimental procedures for details). b Proportion of predicted coiled (unstructured) secondary structural elements in 150-full-length (black) and frameshift (red) mouse C-termini with the largest increase in proline content from full-length to frameshift (left) or all fl and fs C-termini (right). Only fs isoforms confirmed by RNA-seq are included. c Protein stability of GFP-tagged fs U2AF26 or a proline-free variant (in U2AF26 the fs frame is accessible through skipping of two neighboring exons, 6 and 7, exon 7 being the penultimate one). Translation was inhibited by cycloheximide (CHX) and protein degradation was determined by immunoblotting, n = 3. d Protein half-life in 3T3 cells of all measured proteins (All, n = 3573) and genes from the frameshift list (Additional file 2: Table S1) with PSI < 90 (Skipped, n = 192). Spliced genes were further divided in three groups based on the proline content of the alternative frame: (i) lower compared to the original frame (Pfl-Pfs > 3, P-decreased n = 36), (ii) similar proline content (3 > Pfl-Pfs > − 3, P-unchanged, n = 76), and (iii) higher proline content (Pfl-Pfs < − 3, P-rich, n = 80) (*p < 0.05)