The spatial and temporal expression of outer segment proteins during development of Macaca monkey cones

PURPOSE. TO characterize the spatial and temporal expression of key structu ral and phototransduction cascade proteins in the monkey cone outer segment (OS). METHODS. Retinas from Macaca monkeys from ages fetal day (Fd) 89 through ad ulthood were double labeled using immunofluorescence for short (S) or long/ medium (L/M) wavelength-sensitive cone opsin and either a structural protei n (peripherin) or a phototransduction cascade protein (alpha-transducin [al pha-T], phosphodiesterase [PDE], or rhodopsin kinase [RK]). The spatial and temporal patterns of expression for each protein at each age were determin ed and graphed as a percentage of retinal coverage. RESULTS. In both cone types, opsins and phototransduction proteins appear f irst in the fovea and last at the retinal edge. Peripherin appears concomit antly with opsin in both S and L/M cones, but S cones express peripherin an d opsin 1 to 3 weeks before neighboring L/M cones, alpha-T, PDE, and RK are expressed together in the L/M cone OS shortly after L/M opsin appears. Pho totransduction proteins are not expressed in S cones until 1 to 3 weeks aft er the appearance of S opsin and at the same time that neighboring cones ar e expressing both L/M opsin and phototransduction proteins. CONCLUSIONS. The concomitant appearance of opsin and peripherin strongly su ggests roles in promoting the structural integrity of the developing OS. Ph ototransduction cascade proteins appear in the developing OS at the same ti me as one another, but after opsin. The significant lag between their expre ssion and that of S cone opsin indicates that phototransduction proteins ar e not essential for OS formation, nor does opsin expression trigger their e xpression. The different temporal but similar spatial expression patterns o f phototransduction proteins within S and L/M cones suggests that some loca l signal(s) coordinates their appearance.