★ Primary cilia regulate diverse cellular processes, including signal transduction. ★ Photoreceptors possess ciliary outer segment to carry out visual transduction. ★ Visual transduction depends upon trafficking of components to outer segment. ★ Perturbations in the transport result in photoreceptor dysfunction and blindness.
For being a polarized neuron and having a sensory cilium, photoreceptors attract remarkable attention. This is due their highly polarized structure and active visual signal transduction cascades and for the enrichment of complex networks of proteins in the cilium. Structural and functional maintenance of the photoreceptor sensory cilium, also called outer segment, ensures that light signal is received and relayed appropriately to the brain. Any perturbations in the protein content of the outer segment result in photoreceptor dysfunction, degeneration and eventually, blindness. This review focuses on the importance of photoreceptor sensory cilium to carry out signal transduction cascade for vision.