ULTRASTRUCTURAL IMMUNOGOLD LOCALIZATION OF SOME ORGANELLE-TRANSPORT RELEVANT PROTEINS IN WHOLEMOUNTED PERMEABILIZED NONEXTRACTED GOLDFISH XANTHOPHORES

By whole-cell transmission electron microscopy (WCTEM), we recently de monstrated that carotenoid droplets are transported by elongating or r etracting endoplasmic reticular cisternae in goldfish xanthophores. He re we report that permeabilized xanthophores demonstrate immunogold re activity against several proteins involved in organelle translocation. The gold labeling against beta-tubulin and the intermediate filament protein p45a were found on microtubules and intermediate filaments. La beling with antiactin was found on nonidentifiable structures, on vesi cles of unknown origin, occasional labeling on carotenoid droplets, an d on occasional microfilaments. Immunoreactivity was demonstrated with anti-p57 on the carotenoid droplet surface, confirming previous resul ts (Lynch ct al., 1986a,b). Labeling with anti-PCD6 subunit (of the in ositol trisphosphde/ryanodine receptor) was demonstrated on carotenoid droplets suggesting they possess calcium channels. Anti-MAP 1C (dynei n) immunolabeling was generally seen on club-shaped structures in the cytomatrix and on carotenoid droplets. Finally, immunogold labeling wi th anti-MAP 2a + 2b was seen on a meshwork of microfilaments and inter mediate filaments. Finally, this is the first report of a WCTEM techni que for permeabilized cells that reveals immunoreactive elements, orga nelles, and cytomatrix components without the additional requirements of extraction or fracturing.