An Abscisic Acid-Activated and Calcium-Independent Protein Kinase from Guard Cells of Fava Bean
Year: 1996
Type: article
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 threonine 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.
Source: The Plant Cell
DOI: 10.2307/3870474
Authors: J. Li, S. M. Assmann
Institution: Pennsylvania State University
Language: English
Subfield: Plant Science
Domain: Life Sciences
Open Access status: green
Funder: National Science Foundation
OpenAlex ID: W2132767202