Membrane addition to rod photoreceptor outer segments: light stimulates membrane assembly in the absence of increased membrane biosynthesis.

摘要: The effect of light on the biosynthesis and assembly rod photoreceptor outer segment membranes was analyzed in vitro using retinas from Xenopus laevis. number open discs at base used as a morphologic index to evaluate relative differences rates membrane assembly. l ' 2 Assembly stimulated by light, evidenced greater that accumulated light-exposed than maintained under same conditions but darkness. Quantitative autoradiography indicated, however, unlike assembly, incorporation 3 H-leucine or Hmannose into proteins rods nearly identical light-stimulated dark-maintained retinas. Likewise, synthesis ofopsin, protein destined for segment, not affected light. We conclude these studies enhanced rate occurs during early phase diurnal cycle takes place absence an increase opsin, major protein. (INVEST OPHTHALMOL VIS SCI 22:417-427, 1982.)