Proteome expansion by AS. (A) Difference in size between the putative alternative protein and the reference protein. Data are shown for the four main classes of AS events. In the vast majority of cases, the alternative protein would be smaller than the canonical protein. (B) Alternative 13-aa protein isoform in the rpl22 gene. The diagram shows the putative coding sequence in the alternative IR isoform. A stop codon in frame in the intronic region results in the translation of a 13-aa protein. We obtained Ribo-seq support for the 13-aa alternative protein. We also estimated the Ribo-seq coverage of the Rpl22 canonical protein (SPAC11E3.15.1) and the 13-aa alternative isoform (STRG.1957.2) using isoform-specific coding sequences. The values are compared with those for the coding sequences of all transcripts with five or more Ribo-seq reads mapped to the P-site (n = 5669). The gray area covers 90% of cases. (C) Alternative 38-aa protein isoform in the uap2 gene. IR in uap2 generates a shorter coding sequence, encoding a putative 38 aa protein. (D) Alternative 361-aa protein isoform in the etp1 gene. IR in etp1 results in a protein that is 15 aa longer than the reference one.
