Fig. 2.

Cellular distribution and sequence properties of the ubiquitylome. A, Gene Ontology cellular compartment terms associated with ubiquitylated proteins. B, GO biological process terms associated with ubiquitylated proteins. C, Predicted protein secondary structures near ubiquitylation sites. Probabilities for different secondary structures (coil, α-helix and β-strand) of modified lysines were compared with the secondary structure probabilities of all lysines on all proteins identified in this study. D, Amino acid sequence properties of ubiquitylation sites. The heat map shows significant position-specific under- or over-representation of amino acids flanking the modification sites. E, Evolutionary conservation of ubiquitylated lysines and nonubiquitylated lysines on protein orthologs in selected eukaryotic species. Only lysine residues from ubiquitylated proteins identified in this study are compared.