NADPH-protochlorophyllide oxidoreductase: Reciprocal regulation in mono- and dicotyledonean plants.

The influence of light on the expression of NADPH: protochlorophyllide oxidoreductase has been studied in different plant species. The presumptive precursors to this enzyme have been characterized by in vitro translation of poly (A) RNA and immunoprecipitation. Two bands of apparent molecular weights of about 42 000 and 44 000 have been found in light- and dark grown monocotyledonean species, whereas a single band has been observed preferentially in light grown species of dicotyledonean plants. Membrane proteins reacting with the antibody to protochlorophyllide oxidoreductase have been identified by the method of immune blotting. On the basis of these findings it is concluded that protochlorophyllide oxidoreductase proteins are present in the membranes of all illuminated plants for at least several days. The mode of regulation, however, has been found different in mono- and dicotyledonean plants.