Calcium Diffusion Coefficient in Rod Photoreceptor Outer Segments

Cyclic GMP diffusion coefficient in rod photoreceptor outer segments.

Cyclic GMP (cGMP) is the intracellular messenger that mediates phototransduction in retinal rods. As photoisomerizations of rhodopsin molecules are local events, the longitudinal diffusion of cGMP in the rod outer segment should be a contributing factor to the response of the cell to light. We have employed the truncated rod outer segment preparation from bullfrog (Rana catesbeiana) and tiger s...

Methylation of proteins in photoreceptor rod outer segments.

A set of proteins in bovine rod outer segments is specifically methylated by S-adenosyl-L-methionine. The reaction can be demonstrated in the intact retina as well as in fragmented preparations of isolated rod outer segments. The apparent molecular weights of these proteins are 88,000, 61,000, and a subset between 21,000 and 26,000. The Mr = 88,000 protein is shown to be the alpha subunit of th...

Tubulin in bovine retinal rod outer segments.

Bovine rod outer segment (ROS) preparations contain a major 58 kDa protein doublet that was identified by immunoblot as tubulin. Quantification by gel densitometry showed that the total amount of tubulin was 5- to 10-fold higher than that attributable to the rod axoneme, suggesting additional role(s) for tubulin in photoreceptor cells. Approximately 20% of this nonaxonemal tubulin (15% of total...

In reply: expression of transducin in retinal rod photoreceptor outer segments.

Turnover of rod photoreceptor outer segments. II. Membrane addition and loss in relationship to light

The rate of disk addition to rod outer segments (ROS) varies widely in Xenopus laevis tadpoles kept in cyclic light (12L:12D). When measured as radioactive band (3H-band) displacement during the 2nd day after injection of [3H]leucine, 75% of the daily increment of displacement occurred during the first 8 h of light. During the same interval, the number of open disks at the ROS base increased mo...