Supplementary Figure 6: Characterization of protein N termini identified through the 500-Da search in HEK293 cells. | Nature Biotechnology

Supplementary Figure 6: Characterization of protein N termini identified through the 500-Da search in HEK293 cells.

From: A mass-tolerant database search identifies a large proportion of unassigned spectra in shotgun proteomics as modified peptides

Supplementary Figure 6

A-D) N-terminal peptides were identified with four main distinct ∆mass values (-89 Da, -131 Da, +42 Da and unmodified). These values corresponded to protein N-terminal processing events which included methionine cleavage and/or acetylation. E) Summary of protein N-terminal modifications. The majority of proteins (78%) are acetylated in HEK293 cells. F) Venn diagram representation of all the N-terminal peptides demonstrating that a small fraction of protein N termini were actually identified with more than one processing type. In a few cases, all 4 possible N-terminal modifications were present.

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