Detection of cryptic start codons in set2D by 5PSeq

We investigated cryptic transcription start site usage, chromatin organization and post-transcriptional consequences in Saccharomyces cerevisiae. We used 5PSeq approach, which measures ribosome dynamics by sequencing the presence of co-translation mRNA degradation intermediates, to assess if cryptic transcripts are engaged in active translation. We show that chromatin-dependent cryptic transcripts can be recognized by ribosomes and have the potential to produce truncated polypeptides by using downs-stream, in-frame start codons. Our work suggests that a significant fraction of chromatin-dependent internal cryptic promoters are in fact alternative truncated mRNA isoforms. Overall design: We performed 2 biologically independent 5PSeq experiments.