Large-scale proteomics identifies 25% of non-canonical ORFs produce peptides; peptidein classification introduced (nature.com)

• Peptides detected from 2.5% of ncORFs in tryptic and 24.6% in HLA immunopeptidomics data
• Introduction of peptidein concept for microproteins with unclear function
• ORBL metric shows evolutionary constraint for many ncORFs
• OLMALINC peptidein shown to be pan-essential for cell growth

"The TransCODE Consortium analyzed 95,520 proteomics experiments to detect peptides from 7,264 non-canonical open reading frames (ncORFs). About 2.5% were detected in trypsin-digested samples (183 ncORFs) and 24.6% in HLA immunopeptidomics (1,785 ncORFs). They introduce 'peptideins' as microproteins with indeterminate functional potential. An evolutionary metric called ORF relative branch length (ORBL) reveals common constraint. One peptidein from OLMALINC lncRNA shows pan-essential cellular phenotype. Public tools via GENCODE and PeptideAtlas are released."