Light-activated calcium release from sonicated bovine retinal rod outer segment disks.

Calcium trapped within sonicated and resealed bovine rod outer segment disks is released upon light exposure with a stoichiometry of 0.75 +/- 0.05 calcium for each rhodopsin bleached. The amount of calcium liberated is proportional to the amount of bleaching in the range of 20 to 100% bleaching and is relatively insensitive to the internal trapped calcium concentration. The results are obtained using a flow system in which the disk membrane vesicles are adsorbed on glass particle supported by a filter. The external calcium is washed away and subsequent calcium release is monitored by collecting fractions of the effluent before, during, and after light exposure. Disks that are sonicated and allowed to reseal prior to incubation with 45Ca show no change in calcium efflux upon bleaching. The light-activated calcium release is also eliminated if disks sonicated in the presence of 45Ca are treated with a calcium ionophore prior to bleaching. The results demonstrate that the light-released calcium comes from the disks and not from the external disk surface. Lowering temperature to 3--4 degrees C surpresses the light-stimulated release, implicating a transition after the formation of metarhodopsin I in the transport process. The resluts suggest a model for the disk in which each bleached rhodopsin functions as a "one-shot carrier" to transport a single calcium ion across the membrane.

[1]  Helmut Langer,et al.  Biochemistry and Physiology of Visual Pigments , 2012, Springer Berlin Heidelberg.

[2]  H. G. Smith,et al.  Alkyl glucosides as effective solubilizing agents for bovine rhodopsin. A comparison with several commonly used detergents. , 1976, Biochimica et biophysica acta.

[3]  D. Bownds,et al.  Light-sensitive swelling of isolated frog rod outer segments as an in vitro assay for visual transduction and dark adaptation , 1975, The Journal of general physiology.

[4]  K. Hemminki.  Accumulation of calcium by retinal outer segments. , 1975, Acta physiologica Scandinavica.

[5]  A. Cavaggioni,et al.  Effect of strong illumination on the ion efflux from the isolated discs of frog photoreceptors. , 1975, Biochimica et biophysica acta.

[6]  P. Mandel,et al.  Role of light and rhodopsin phosphorylation in control of permeability of retinal rod outer segment disks to Ca2+ , 1975, Nature.

[7]  H. G. Smith,et al.  The isolation and purification of osmotically intact discs from retinal rod outer segments. , 1975, Experimental eye research.

[8]  K. Hemminki.  Light-induced decrease in calcium binding to isolated bovine photoreceptors , 1975, Vision Research.

[9]  B. Litman.  Determination of molecular asymmetry in the phosphatidylethanolamine surface distribution in mixed phospholipid vesicles. , 1974, Biochemistry.

[10]  T. Hendriks,et al.  Biochemical aspects of the visual process. XXV. Light-induced calcium movements in isolated frog rod outer segments , 1974 .

[11]  W. A. Hagins,et al.  Proceedings: A role for Ca2+ in excitation of retinal rods and cones. , 1974, Experimental eye research.

[12]  W. Mason,et al.  Ion Fluxes in Disk Membranes of Retinal Rod Outer Segments , 1974, Nature.

[13]  M. Poo,et al.  Lateral diffusion of rhodopsin in Necturus rods , 1973 .

[14]  W. Mason,et al.  Resealing properties of biological membranes. , 1973, Nature: New biology.

[15]  R. Cone,et al.  Dark Ionic Flux and the Effects of Light in Isolated Rod Outer Segments , 1972, The Journal of general physiology.

[16]  W. H. Miller,et al.  Calcium binding to retinal rod disk membranes. , 1972, Biochimica et biophysica acta.

[17]  W. Robinson,et al.  Characterization and Analysis of Frog Photoreceptor Membranes , 1971, The Journal of general physiology.

[18]  T. Tomita,et al.  Studies on the mass receptor potential of the isolated frog retina. II. On the basis of the ionic mechanism. , 1969, Vision research.

[19]  G. Wald.  The Molecular Basis of Visual Excitation , 1968, Nature.

[20]  R Hubbard,et al.  THE ACTION OF LIGHT ON RHODOPSIN. , 1958, Proceedings of the National Academy of Sciences of the United States of America.

[21]  R. Hubbard,et al.  THE RHODOPSIN SYSTEM OF THE SQUID , 1958, The Journal of general physiology.

[22]  Oliver H. Lowry,et al.  Protein measurement with the Folin phenol reagent. , 1951, The Journal of biological chemistry.

[23]  W. A. Hagins.  The visual process: Excitatory mechanisms in the primary receptor cells. , 1972, Annual review of biophysics and bioengineering.

[24]  E. W. Abrahamson,et al.  The photochemical and macromolecular aspects of vision. , 1967, Progress in biophysics and molecular biology.