Phosphorylation sites, phosphopeptides, and site-discriminating ions identified in iFGF13 proteins from NaV channel complexes purified from adult mouse left ventricles using MS
| Phosphorylation site(s) . | Phosphopeptide sequence . | m/z (charge) . | Ascore . | b ion . | Phospho b ion . | y ion . | Phospho y ion . |
|---|---|---|---|---|---|---|---|
| S35 | 33-QD(pS)IQSAELK | 828.936 (+2) | 10 | b2 (+1) | b5 | y7 (+1) | y8 (+1) |
| S38 | 33-QDSIQ(pS)AELK | 828.933 (+2) | 38 | b5 (+1) | (−) | y4 (+1) | (−) |
| S35 + S38 | 33-QD(pS)IQ(pS)AELK | 868.917 (+2) | 1,000; 1,000 | b2 (+1) | b5 | y4 (+1) | y5; y8 |
| S218 | 216-EP(pS)LHDLTEFSR | 870.414 (+2) | 54 | b1 (+1) | b7 | y9 (+1) | (−) |
| S230 + T232 | 228-SG(pS)G(pT)PTKSR | 532.593 (+3) | 11; 14 | b2 | (−) | y5 (+2) | (−) |
| T232 | 228-SGSG(pT)PTKSR | 505.936 (+3) | 8 | b4 | (−) | y5 (+2) | (−) |
| S238 | 236-SR(pS)VSGVLNGGK | 566.982 (+3) | 9 | b2 | b3 (+2) | y9 | (−) |
| S240 | 238-SV(pS)GVLNGGK | 728.401 (+2) | 1000 | b2 | (−) | y7 | (−) |
| S250 | 248-SM(pS)HNEST | 609.238 (+2) | 2 | b2 | b5 (+2) | (−) | (−) |
| T255 | 248-SMSHNES(pT) | 601.240 (+2) | 12 | b7 (+2) | (−) | (−) | (−) |
| S250 + S255 | 248-SM(pS)HNES(pT) | 641.226 (+2) | 0; 0 | b2 | (−) | (−) | (−) |
| Phosphorylation site(s) . | Phosphopeptide sequence . | m/z (charge) . | Ascore . | b ion . | Phospho b ion . | y ion . | Phospho y ion . |
|---|---|---|---|---|---|---|---|
| S35 | 33-QD(pS)IQSAELK | 828.936 (+2) | 10 | b2 (+1) | b5 | y7 (+1) | y8 (+1) |
| S38 | 33-QDSIQ(pS)AELK | 828.933 (+2) | 38 | b5 (+1) | (−) | y4 (+1) | (−) |
| S35 + S38 | 33-QD(pS)IQ(pS)AELK | 868.917 (+2) | 1,000; 1,000 | b2 (+1) | b5 | y4 (+1) | y5; y8 |
| S218 | 216-EP(pS)LHDLTEFSR | 870.414 (+2) | 54 | b1 (+1) | b7 | y9 (+1) | (−) |
| S230 + T232 | 228-SG(pS)G(pT)PTKSR | 532.593 (+3) | 11; 14 | b2 | (−) | y5 (+2) | (−) |
| T232 | 228-SGSG(pT)PTKSR | 505.936 (+3) | 8 | b4 | (−) | y5 (+2) | (−) |
| S238 | 236-SR(pS)VSGVLNGGK | 566.982 (+3) | 9 | b2 | b3 (+2) | y9 | (−) |
| S240 | 238-SV(pS)GVLNGGK | 728.401 (+2) | 1000 | b2 | (−) | y7 | (−) |
| S250 | 248-SM(pS)HNEST | 609.238 (+2) | 2 | b2 | b5 (+2) | (−) | (−) |
| T255 | 248-SMSHNES(pT) | 601.240 (+2) | 12 | b7 (+2) | (−) | (−) | (−) |
| S250 + S255 | 248-SM(pS)HNES(pT) | 641.226 (+2) | 0; 0 | b2 | (−) | (−) | (−) |
The site-discriminating ions observed in MS/MS spectra of each annotated iFGF13 phosphopeptide support the assignment of the indicated phosphorylation site(s). The PEAKS Ascore is a quality indicator of site localization. The manually verified charge state of unphosphorylated and phosphorylated site-discriminating b and y ions is reported in parentheses. The (−) symbol indicates that the ion was not detected.