Analysis of internal protein-altered regions across proteins in GENCODE. (A) Frequencies of the categories of the splicing mechanism underlying internal protein sequence changes, split by their protein-coding impact (deletion, insertion, and substitution). All sequence regions involve a reference-alternative isoform pair. (B) Frequency of compound splicing events across the altered internal regions. (C) The proportion of each internal protein region type for which there exists a split codon pattern near its boundaries that would cause a single AA difference, or “ragged” codon. (D) Examples of successive frameshifting (“snapback” frameshift) that leads to an affected protein region that is wholly internal to the protein, for genes FAS and PLEKHJ1.
