Rapid Phytochrome-Controlled Protein Phosphorylation and Dephosphorylation in Avena sativa L.

The time course for in vivo changes in the protein phosphorylation pattern was measured after red and red/far-red light. Avena coleoptile tips were incubated in 32P-labeled phosphate and irradiated. The supernatant fractions of homogenates were subjected to SDS-poly-acrylamide gel electrophoresis and then autoradiographed. Within seconds, the radioactive label of two proteins decreased and the radioactive label of one protein increased. These data suggest that the phosphorylation states for these proteins may be under phytochrome control.