A gene of a membrane protein

Arehaerhedopsin-4(AR4)

was expressed into anH．salinarum strain L133

which is negative for synthesis of bacterio-opsin and whose lipid environment is free of carotenoid．The carotenoid has three characterized absorption peaks at 480

508 and 544 nm which cover the absorption peak of membrane protein AR4 at 5700 nm at the ground state．In contrast to the wide-type AR4 isolated from the conventional strain H．sp．xz515

the recombinant AR4 removed the binded carotenoid．The underlying photochromic properties of the recombinant AR4 was thus improved

and the contrast between M410 intermediate and ground state was greatly enhanced．Composite films were further made by embedding the recombinant AR4 into pely(vinyl alcohd)(PVA)．By enhancing its pH

the decay of the M intermediate Was slowed down．A simple pattern recording as an optical information storage material was also realized by the compostie films．During this process

Iight was illuminated into the composite covered with a mask

and the pattern in the mask was observed even after removing the mask．Hence．this paper demonstrates that the polymer technique and gene engineering could be combined tO prepare information materials with both the biological activities of proteins and the good processing properties of polymers．