Table 1. Identification of Cep68 phosphorylation sites in vivo by mass spectrometry.
FLAG-tagged Cep68 was immunoprecipitated from HEK293T cells that were either untreated or treated with BI2536 (a PLK1 inhibitor) for 16 hours. Note that PLK1 inhibition results in prometaphase arrest. The table lists the number of spectra matching phosphorylated peptides as a fraction of total spectra detected for peptides bearing each residue and their corresponding modification percentage. Ser332 was identified as a phosphorylated residue in untreated cells, but not in cells treated with BI2536.
| Residue and modification | Untreated | PLK inhibition | Surrounding Sequence |
|---|---|---|---|
| T106 | 1/664 | 0/972 |
|
| S109 | 17/664 | 17/972 |
|
| S126 | 1/128 | 3/286 |
|
| S136 | 0/128 | 4/286 |
|
| S186 | 0/279 | 1/482 |
|
| S249 | 0/61 | 8/113 |
|
| S268 | 3/50 | 6/40 |
|
| Y273 | 0/50 | 8/40 |
|
| S285 | 0/50 | 5/40 |
|
| S332 | 1/147 | 0/215 |
|
| S340 | 0/147 | 2/215 |
|
| S342 | 9/147 | 12/215 |
|
| S354 | 3/203 | 6/188 |
|
| S374 | 0/144 | 1/89 |
|
| S435 | 2/419 | 8/437 |
|
| S472 | 4/37 | 2/47 |
|
| S478 | 23/37 | 32/47 |
|