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. Author manuscript; available in PMC: 2022 Apr 2.
Published in final edited form as: J Proteome Res. 2022 Mar 15;21(4):1189–1195. doi: 10.1021/acs.jproteome.1c00771

Table 2.

Examples of ProForma 2.0 Notations Demonstrating the Various Features of the Specificationa

feature example section
CV/ontology modification names EM[Oxidation]EVEES[Phospho]PEK 4.2.1
CV/ontology protein modification accession numbers EM[MOD:00719]EVEES[MOD:00046]PEK 4.2.2
cross-link within the same peptide EMEVTK[XLMOD:02001#XL1]SESPEK[#XL1] 4.2.3.1
interchain cross-links SEK[XLMOD:02001#XL1]UENCE//EMEVTK[#XL1]SESPEK 4.2.3.2
disulfide linkages EVTSEKC[MOD:00034#XL1]LEMSC[#XL1]EFD 4.2.3.3
branched peptides ETFGD[MOD:00093#BRANCH]//R[#BRANCH]ATER 4.2.4
glycans using the GNO ontology as CV NEEYN[GNO:G59626AS]K 4.2.5
delta mass notation for modifications EM[+15.9949]EVEES[+79.9663]PEK 4.2.6
specifying a gap of known mass RTAAX[+367.0537]WT 4.2.7
support for elemental formulas SEQUEN[Formula:C12H20O2]CE 4.2.8
glycan composition SEQUEN[Glycan:HexNAc1Hex2]CE 4.2.9
N-terminal and C-terminal modifications [iTRAQ4plex]-EMEVNESPEK 4.3.1
labile modifications {Glycan:Hex}EMEVNESPEK 4.3.2
unknown modification position [Phospho]?EMEVTSESPEK 4.4.1
possible set of modification positions EMEVT[#g1]S[#g1]ES[Phospho#g1]PEK 4.4.2
ranges of positions for the modifications PROT(ESFRMS)[+19.0523]ISK 4.4.3
modification position preference and localization scores EMEVT[#g1(0.01)]S[#g1(0.09)]ES[Phospho#g1(0.90)]PEK 4.4.4
scoring for ranges of positions for a modification PROT(ESFRMS)[+19.0523#g1(0.01)]ISK[#g1(0.99)] 4.4.5
isotopes <13C>ATPEILTVNSIGQLK 4.6.1
fixed protein modifications <[MOD:01090]@C>ATPEILTCNSIGCLK 4.6.2
ambiguity in the order of the amino acid sequence (?DQ)NGTWEMESNENFEGYMK 4.7
information tag ELVIS[Phospho|INFO:newly discovered]K 4.8
joint representation of experimental data and interpretation ELVIS[Phospho|Obs:+79.978]K 4.9
representation of ion charges EMEVEESPEK/2 7.1
multiple peptidoforms assigned to chimeric spectra EMEVEESPEK/2+ELVISLIVER/3 7.1
a

For each feature listed in the first column, there is a representative example in the second column showing the encoding. The “section” column provides the location in the PSI specification document where the feature is explained in detail (Supporting Information).