Abstract
Abscisic acid (ABA) regulation of stomatal aperture is known to involve both Ca2+-dependent and Ca2+-independent signal transduction pathways. Electrophysiological studies suggest that protein phosphorylation is involved in ABA action in guard cells. Using biochemical approaches, we identified an ABA-activated and Ca2+-independent protein kinase (AAPK) from guard cell protoplasts of fava bean. Autophosphorylation of AAPK was rapidly (∼1 min) activated by ABA in a Ca2+-independent manner. ABA-activated autophosphorylation of AAPK occurred on serine but not on tyrosine residues and appeared to be guard cell specific. AAPK phosphorylated histone type III-S on serine and tnreonine residues, and its activity toward histone type III-S was markedly stimulated in ABA-treated guard cell protoplasts. Our results suggest that AAPK may play an important role in the Ca2+-independent ABA signaling pathways of guard cells.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2359-2368 |
| Number of pages | 10 |
| Journal | Plant Cell |
| Volume | 8 |
| Issue number | 12 |
| DOIs | |
| State | Published - Dec 1996 |
All Science Journal Classification (ASJC) codes
- Plant Science