Table 1.
Competitive displacement of [35S]PSK-α by various PSK analogs
| Competitor | Bound [35S]PSK-α, relative value | Mitogenic activity (ED50), nM* |
|---|---|---|
| PSK-α | 0 | 4 |
| PSK-β | 58.2 | 50 |
| PSK-α-(1–3) | 26.2 | 20 |
| PSK-α-(2–5) | 118.1 | >1,000 |
| PSK-α-(1–2) | 103.6 | >1,000 |
| [OH]PSK-α | 97.6 | >1,000 |
| Naphthaleneacetic acid | 114.5 | — |
| N6-Benzyladenine | 102.2 | — |
| Control | 100.0 | — |
Rice cells were incubated with 32 nM [35S]PSK-α in the presence of 3.2 μM various synthetic PSK analogs or 1.0 mg/liter naphthaleneacetic acid or N6-benzyladenine. After 240 min, cells were collected by filtration and analyzed for radioactivity. Abbreviations: PSK-α-(1–3), Tyr(SO3H)-Ile-Tyr(SO3H); PSK-α-(2–5), Ile-Tyr(SO3H)-Thr-Gln; PSK-α-(1–2), Tyr(SO3H)-Ile; [OH]PSK-α, Tyr-Ile-Tyr-Thr-Gln.
*
See ref. 13.