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 endop lasmic reticulum (ER) in neuronal cells; however, the mechanisms maintainin g Ca2+ channel position within the ER membrane are elusive. By means of con focal 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 d istinct microdomains of the ER next to the photoreceptive microvilli. After incubation with cytochalasin B or cytochalasin D, which results in a disru ption of F-actin, RyRs were distributed through the entire ER, suggesting t hat RyRs a re positioned with in honeybee visual cells by interaction with the F-actin system. (C) 2001 Elsevier Science Ireland Ltd. All rights reser ved.