Protein phosphorylation in isolated nuclei from etiolated Avena seedlings Effects of red/far‐red light and cholera toxin

Abstract
We have studied the phosphorylation/dephosphorylation of several nuclear proteins in isolated nuclei from etiolated Avena seedlings as a function of red/far‐red light. The effect of stimulatory (ADP‐ribosylation by cholera toxin) or inhibitory (GDPβS) conditions for GTP‐binding proteins was also studied. Red or far‐red light enhanced the phosphorylation level of 2 nuclear proteins with molecular masses of 75 and 60 kDa. The phosphorylation pattern was affected by the addition of cholera toxin or GDPβS to the isolated nuclei. At least 2 proteins with molecular masses of 24 and 75 kDa cross‐reacted by Westerrs blot with GTP‐binding protein antibodies.