A database to predict AltORFs in human mRNAs.

(A) A canonical mRNA and its possible AltORFs. The RefORF is the main protein coding ORF annotated in current nucleotide databases. An AltORF is a nucleotide region comprised between an AUG codon and a stop codon distinct from the RefORF and is predicted to encode an alternative protein. AltORFs may be localized in 5′ UTRs, overlapping the 5′UTR and the RefORF, overlapping the RefORF, overlapping the RefORF and the 3′UTR, or in the 3′UTR. (B) Representation of the database generation process. Distinct AltORFs number indicates the total number of predicted AltORFs that encode alternative proteins with unique amino acid sequences. Since an AltORF may be present in several transcripts, the total number of AltORFs in the transcriptome exceeds the number of distinct AltORFs. (C) Distribution in % of AltORFs. (D,E) Distribution of the number of predicted AltORFs per mRNA in (D) and the size distribution of AltORFs (empty bars, left and bottom scale) compared to RefORFs (grey bars, right and top scale) in (E). Boxes and arrows indicate the median.