Which protein is known to transport all-trans-retinal within photoreceptors and is associated with Stargardt's disease?

ABCA4 is the protein responsible for transporting all-trans-retinal within photoreceptors and is directly associated with Stargardt's disease. This protein functions primarily in the photoreceptor cells of the retina, where it plays a critical role in the visual cycle by transporting retinaldehyde derivatives, such as all-trans-retinal, from the disc membranes of the photoreceptors back to the cytoplasm. A malfunction or mutation in the ABCA4 gene can lead to the accumulation of toxic byproducts in the retinal cells, which is a significant factor contributing to the pathology of Stargardt's disease, a form of inherited macular degeneration.

In Stargardt's disease, this accumulation ultimately results in the degeneration of the retinal pigment epithelium and photoreceptor cells, leading to vision loss. Therefore, understanding the role of ABCA4 in retinal function and disease is crucial for grasping the mechanisms underlying visual impairments associated with this condition.