Detection of Some Conserved Domains in Phytochrome-like Proteins from Algae

Abstract

Summary Proteins extracted from various brown, red and green algae showed positive cross-reactivity against several monoclonal antibodies directed specifically to certain parts of phytochrome from etiolated higher plants, viz., the region of the N-terminal (antibodies Z2B3 and Z4B5), the bilatriene chromophore region (Z3B1), the region between the chromophore and the C-terminal (ACC5 and AFD4), and the C-terminal region (A2A3 and Z4A5). The chromophore region appears to be highly conserved since cross-reactivity was found in all cases. The monoclonal antibodies directed to the N-terminal region of phytochrome from etiolated Avena and Zea bound to the proteins from green and red algae, but not to those from brown algae, and the antibodies directed to the C-terminal bound to all green algae, but only to one red alga ( Corallina ). We conclude that the phytochrome-like proteins extracted from algae are immunochemically similar to phytochrome from etiolated higher plants. While several domains have been conserved, some immunochemical differences have been observed between the phytochrome-like proteins from red and green algae on the one hand, and the protein from brown algae on the other hand.