Disruption of actin filaments causes redistribution of ryanodine receptor Ca2+ channels in honeybee photoreceptor cells.

Ca2+ channels often have a restricted distribution over the elaborate endoplasmic reticulum (ER) in neuronal cells; however, the mechanisms maintaining Ca2+ channel position within the ER membrane are elusive. By means of confocal immunofluorescence microscopy, ryanodine receptor (RyR) Ca2+ channels were localized in honeybee photoreceptors, and the role of actin filaments in RyR positioning was examined. In control cells, RyRs were enriched at distinct microdomains of the ER next to the photoreceptive microvilli. After incubation with cytochalasin B or cytochalasin D, which results in a disruption of F-actin, RyRs were distributed through the entire ER, suggesting that RyRs are positioned within honeybee visual cells by interaction with the F-actin system.