Table I. Src specific kinase activity in unsynchronized and mitotic PTPα expressor and knockout cell lines.
| PTPα | Cell line | PTPα expression levela | Relative Src kinase specific activityb |
|
|---|---|---|---|---|
| Unsynchronized | Mitotic | |||
| Endogenous | NIH(pTet-Splice/cos)1 | 1 | 1 | 2.3 ± 0.1 |
| Overexpressed PTPα | NIH(pNTPTPα/cos)1 | 5.8 ± 0.4 | 1.8 ± 0.1 | 3.3 ± 0.1 |
| Overexpressed PTPα-HA | NIH(pTPTPα/cos)1 | 8.6 ± 0.5 | 4.2 ± 0.2 | 7.5 ± 0.3 |
| Overexpressed PTPα(Y789F)-HA | NIH(pTPTPα/Y789F/cos)1 | 8.0 ± 0.5 | 1.2 ± 0.1 | 2.3 ± 0.1 |
| PTPα+/+ | 3αP9 | 1.05 ± 0.05 | 1.1 ± 0.1 | 1.9 ± 0.1 |
| PTPα–/– | 3BP2 | <0.1c | 0.6 ± 0.1 | 0.7 ± 0.1 |
aFor the overexpressor lines, the expression levels under the induced experimental conditions are listed. Values are averages (± SEM) of at least two experiments normalized to the level of endogenous PTPα.
bSrc specific activity for phosphorylation of enolase was measured in experiments like those shown in Figures 3 and 9. Values are averages (± SEM) of two experiments normalized to the specific activity of Src in control NIH 3T3 cells that had been transfected with an empty vector.
cNo expression was detectable.