title: Amino termini of many yeast proteins map to downstream start codons.
abstract: Comprehensive knowledge of proteome complexity is crucial to understanding cell function. Amino termini of yeast proteins were identified through peptide mass spectrometry on glutaraldehyde-treated cell lysates as well as a parallel assessment of publicly deposited spectra. An unexpectedly large fraction of detected amino-terminal peptides (35%) mapped to translation initiation at AUG codons downstream of the annotated start codon. Many of the implicated genes have suboptimal sequence contexts for translation initiation near their annotated AUG, and their ribosome profiles show elevated tag densities consistent with translation initiation at downstream AUGs as well as their annotated AUGs. These data suggest that a significant fraction of the yeast proteome derives from initiation at downstream AUGs, increasing significantly the repertoire of encoded proteins and their potential functions and cellular localizations.
authors.affiliation: Department of Biology, Wesleyan University, Middletown, Connecticut 06459, United States.
authors.forename: Claire T
authors.initials: CT
authors.lastname: Fournier
authors.forename: Justin J
authors.initials: JJ
authors.lastname: Cherny
authors.forename: Kris
authors.initials: K
authors.lastname: Truncali
authors.forename: Adam
authors.initials: A
authors.lastname: Robbins-Pianka
authors.forename: Miin S
authors.initials: MS
authors.lastname: Lin
authors.forename: Danny
authors.initials: D
authors.lastname: Krizanc
authors.forename: Michael P
authors.initials: MP
authors.lastname: Weir
mesh_terms: D000107:Acetylation; D000465:Algorithms; D018387:Codon, Initiator / Q000235:genetics / Q000378:metabolism*; D030562:Databases, Protein; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D005976:Glutaral / Q000378:metabolism; D058977:Molecular Sequence Annotation; D016366:Open Reading Frames; D010442:Peptide Chain Initiation, Translational; D010449:Peptide Mapping / Q000379:methods*; D059748:Proteolysis; D020543:Proteome / Q000032:analysis* / Q000378:metabolism; D040901:Proteomics / Q000379:methods; D012270:Ribosomes / Q000378:metabolism; D004718:Saccharomycetales / Q000235:genetics / Q000378:metabolism*; D020539:Sequence Analysis, Protein; D053719:Tandem Mass Spectrometry
chemical_list: D018387:Codon, Initiator; D005656:Fungal Proteins; D020543:Proteome; D005976:Glutaral