G-proteins in etiolated Avena seedlings. Possible phytochrome regulation.

The molecular mechanism of light signal transduction in plants mediated by the photosensor phytochrome is not well understood. The possibility that phytochrome initiates the signal transduction chain by modulating a G-protein-like receptor is examined in the present work. Etiolated Avena seedlings contain G-proteins as examined in terms of the binding of GTP as well as by cross-reaction with mammalian G-protein antibodies. The binding of GTP was regulated in vivo by red/far-red light. The possible involvement of G-proteins in the phytochrome-mediated signal transduction in etiolated Avena seedlings has been implicated from the study of the light regulated expression of the Cab and phy genes.