CRYSTAL STRUCTURE OF BACTERIORHODOPSIN MUTANT I148A CRYSTALLIZED FROM BICELLES TRANSPORT PROTEIN, BACTERIORHODOPSIN, PACKING FORCE, VAN DER WAALS, EVOLUTIONARY CONSTRAINT, MEMBRANE PROTEIN, INTEGRAL MEMBRANE PROTEIN, HELICAL MEMBRANE PROTEIN, PROTON TRANSPORT, CELL MEMBRANE, CHROMOPHORE, HYDROGEN ION TRANSPORT, ION TRANSPORT, MEMBRANE, PHOTORECEPTOR PROTEIN, PYRROLIDONE CARBOXYLIC ACID, RECEPTOR, RETINAL PROTEIN, SENSORY TRANSDUCTION, TRANSMEMBRANE, TRANSPORT 3HAQ