PROTEIN-PHOSPHORYLATION IN ISOLATED-NUCLEI FROM ETIOLATED AVENA SEEDLINGS - EFFECTS OF RED FAR-RED LIGHT AND CHOLERA-TOXIN

We have studied the phosphorylation/dephosphorylation of several nuclear proteins is 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 (GDP-beta-S) 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 GDP-beta-S to the isolated nuclei. At least 2 proteins with molecular masses of 24 and 75 kDa cross-reacted by Western blot with GTP-binding protein antibodies.