[Photoreceptor membrane assymetric structure in separated phase state]

The structure of unbleached bovine retinal rod photoreceptor membranes isolated in ficoli density gradient has been studied by means of small-angle X-ray diffraction methods. Samples were prepared in the form of thin multilamellar films of photoreceptor membranes in phase-separated state induced by partial dehydration. Diffraction data were collected using diffractometer with linear position-sensitive detector. Phase signs of structure amplitude were determined by method [7] and membrane lamellar electron density distribution was calculated at 1, 7 nm resolution. The results obtained showed photoreceptor membranes isolated in ficoli density gradient to have asymmetric structure which differed from that of photoreceptor membranes isolated in sucrose density gradient [1]. The asymmetry observed may be accounted for different content of lipid L alpha and L beta phases in cytoplasmic and intradisk membrane layers. It may be assumed that ficoli helps to support membrane native structure.