Phosphorylation of Avena phytochrome in vitro as a probe of light-induced conformational changes.
YS Wong, HC Cheng, DA Walsh, JC Lagarias
J Biol Chem | Published : 1986
A polycation-dependent protein kinase was found to be associated with purified phytochrome preparations from etiolated Avena seedlings. This kinase and three mammalian protein kinases, the catalytic subunit of cAMP-dependent protein kinase, cGMP-dependent protein kinase, and a Ca2+-activated phospholipid-dependent protein kinase, were used to probe light-induced conformational changes in 124-kilodalton Avena phytochrome in vitro. The red absorbing form of phytochrome (Pr) was found to be a substrate for all four protein kinases. Although the far-red absorbing form of phytochrome (Pfr) was as good a substrate as Pr with the cAMP-dependent protein kinase, the Pfr form was poorly phosphorylated..View full abstract