SOME OBSERVATIONS ON THE MORPHOGENESIS OF LATTICE STRUCTURE IN THE PURPLE MEMBRANE

Abstract— The formation process of purple membrane was studied morphologically by freeze-fracture and etching methods. The bacteria, H. halobium R₁, cultured in the medium containing 2m M nicotine, did not show the hexagonal structure of purple membrane, but a particle free area was frequently observed in the plasma membrane. However, within 24h after returning to the normal medium, hexagonal and triclinic lattices with spacings of 6 to 8nm occurred as small patches on the P face of the plasma membrane. Furthermore, it was revealed that the retinal was not required for the formation of the two-dimensional hexagonal lattice structure of purple membrane, since the mutant bacteria, H. halobium R₁mW, lacking the ability of retinal synthesis, displayed a similar lattice. The other mutant, H. halobium R₁mR, lacking the ability of bacterio-opsin synthesis, never showed any highly ordered arrangement. This evidence suggests that membrane proteins other than bacterio-opsin or bacteriorhodopsin do not form highly ordered lattices in the membrane.