PKS1, a Substrate Phosphorylated by Phytochrome That Modulates Light Signaling in Arabidopsis
Christian Fankhauser,
1
Kuo-Chen Yeh,
3
J. Clark ,
Lagarias,
3
Hong Zhang,
4
Tedd D. Elich,
1*
Joanne Chory
12
Plants constantly monitor their light environment in order to grow
and develop optimally, in part through use of the phytochromes, which
sense red/far-red light. A phytochrome binding protein, PKS1
(phytochrome kinase substrate 1), was identified that is a substrate
for light-regulated phytochrome kinase activity in vitro. In vivo
experiments suggest that PKS1 is phosphorylated in a
phytochrome-dependent manner and negatively regulates phytochrome signaling. The data suggest that phytochromes signal by
serine-threonine phosphorylation.
1 Plant Biology Laboratory,
2 Howard Hughes Medical Institute, Salk Institute,
La Jolla, CA 92037, USA.
3 Section of Molecular and
Cellular Biology, University of California, Davis, CA 95616, USA.
4 Department of Biological Sciences, Texas Tech
University, Lubbock, TX 79409, USA.
*
Present address: Monsanto Company, 700 Chesterfield Parkway,
North St. Louis, MO 63198, USA.
To whom correspondence should be addressed. E-mail:
chory{at}salk.edu
