Storage sites for retinyl esters called retinosomes (red) do not colocalize with organelles such as the Golgi (blue).

Like explorers spotting an uncharted island on the horizon, Imanishi et al. (page 373) have identified a previously unknown cellular structure that could be an entirely new organelle. The structure, located in cells of the retinal pigment epithelium, appears to be an essential waypoint in the retinoid cycle—the series of chemical reactions that regenerates 11-cis-retinal, the chromophore for rhodopsin, after light converts it to all-trans-retinal.

Isolated retinas do not survive long outside of the eye, complicating studies of retinal biology. The authors circumvented this problem by looking directly into the eyes of live mice with two-photon fluorescent microscopy. Retinol and retinyl esters show weak intrinsic fluorescence, producing high-resolution images of intact retinal cells and revealing a fence-like intracellular structure dubbed the...

The Rockefeller University Press
2004
The Rockefeller University Press
2004
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