Table III. Endogenous phosphopeptide identification.
Mascot scores of first to third hits (columns 6 to 8) are accompanied by expectation values shown in parentheses. N-term, N-terminal flanking amino acid (“Signal” indicates that the peptide is flanked by signal sequence); C-term, C-terminal flanking amino acid. Identified phosphorylation sites are marked in bold and underlined. In the last column, the asterisk indicates that either of the two N-terminal serine residues is phosphorylated but not uniquely determined. CT, calcitonin; SgII, secretogranin II.
| Method | Precursor | m/z (obsd.) | z | Mr (calc.) (Da) | 1st Hit | 2nd Hit | 3rd Hit | N-term | Sequence | C-term | Reference |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Unequivocal localization | |||||||||||
| CID | CgB | 1175.887 | 6 | 7049.271 | 94 (1.9E-05) | 49 (0.6) | 28 (77) | K | SAEFPDFYDSEEPVSTHQEAENEKDRADQTVLTEDEKKELENLAAMDLELQKIAEKFSQR-NH2 | G | (27) |
| CID | CgB | 1222.937 | 5 | 6109.646 | 60 (3.6E-02) | 9 (4.5E+03) | 6 (8.0E+03) | R | ASEEEPEYGEEIKGYPGVQAPEDLEWERYRGRGSEEYRAPRPQSEESWDEE | D | (27) |
| CID | CgB | 845.549 | 6 | 5067.250 | 82 (2.2E-04) | 45 (1) | 35 (10) | R | LLRDPADASEAHESSSRGEAGAPGEEDIQGPTKADTEKWAEGGGHSRE | R | |
| ETD | CgB | 938.004 | 5 | 4684.981 | 109 (2.9E-07) | 60 (0.023) | 39 (3.1) | R | DPADASEAHESSSRGEAGAPGEEDIQGPTKADTEKWAEGGGHSRE | R | |
| ETD | CgB | 747.137 | 5 | 3730.647 | 136 (6.5E-10) | 12 (1.6E+03) | 4 (8.7E+03) | R | NYPSLELDKMAHGYGEESEEERGLEPGKGRHH | R | (26) |
| ETD | CT | 1260.409 | 5 | 6297.006 | 65 (0.016) | 42 (3.1) | 41 (3.8) | Signal | APFRSALESSPADPATLSEDEARLLLAALVQDYVQMKASELEQEQEREGSSLDSPRS | K | |
| Ambiguous localization | |||||||||||
| ETD | CgB | 845.006 | 5 | 4219.991 | 139 (4.3E-10) | 138 (4.4E-10) | 67 (0.0063) | R | GEDSSEEKHLEEPGETQNAFLNERKQASAIKKEELVA | R | (27) * |
| CID | SgII | 1138.077 | 7 | 7959.485 | 78 (0.00075) | 71 (0.003) | 71 (0.003) | R | ERMDEEQKLYTDDEDDIYKANNIAYEDVVGGEDWNPVEEKIESQTQEEVRDSKENIEKNEQINDEM | K | |
| CID | SgII | 1280.066 | 6 | 7674.341 | 103 (2.5E-06) | 95 (1.5E-05) | 95 (1.5E-05) | R | MDEEQKLYTDDEDDIYKANNIAYEDVVGGEDWNPVEEKIESQTQEEVRDSKENIEKNEQINDEM | K | |
| ETD | SgII | 1030.079 | 5 | 5145.363 | 70 (0.0038) | 70 (0.0038) | 63 (0.018) | R | ALEYIENLRQQAHKEESSPDYNPYQGVSVPLQQKENGDESHLPE | R | |
| CID | VGF | 1117.343 | 6 | 6698.003 | 168 (7.8E-13) | 168 (7.8E-13) | 168 (7.8E-13) | R | SQEETPGHRRKEAEGTEEGGEEEDDEEMDPQTIDSLIELSTKLHLPADDVVSIIEEVEE | K | |
| ETD | VGF | 807.197 | 5 | 4030.954 | 115 (9.2E-08) | 105 (8.1E-07) | 0.5 (2.5E+04) | Signal | APPGRPEAQPPPLSSEHKEPVAGDAVPGPKDGSAPEVRGA | R | |
| ETD | VGF | 937.707 | 4 | 3746.794 | 91 (2.3E-05) | 77 (0.0005) | 6 (7.0E+03) | Signal | APPGRPEAQPPPLSSEHKEPVAGDAVPGPKDGSAPEV | R |