The ATP-Binding Cassette Transporter ABCA4: Structural and Functional Properties and Role in Retinal Disease

  • Yaroslav Tsybovsky
  • Robert S. Molday
  • Krzysztof Palczewski
Conference paper
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 703)


ATP-binding cassette transporters (ABC transporters) utilize the energy of ATP hydrolysis to translocate an unusually diverse set of substrates across cellular membranes. ABCA4, also known as ABCR, is a ∼250 kDa single-chain ABC transporter localized to the disk margins of vertebrate photoreceptor outer segments. It is composed of two symmetrically organized halves, each comprising six membrane-spanning helices, a large glycosylated exocytoplasmic domain located inside the disk, and a cytoplasmic domain with an ATP-binding cassette. Hundreds of mutations in ABCA4 are known to cause impaired vision and blindness such as in Stargardt disease as well as related disorders. Biochemical and animal model studies in combination with patient analyses suggest that the natural substrate of ABCA4 is retinylidene-phosphatidylethanolamine (N-retinylidene-PE), a precursor of potentially toxic diretinal compounds. ABCA4 prevents accumulation of N-retinylidene-PE inside the disks by transporting it to the cytoplasmic side of the disk membrane where it can dissociate, allowing the released all-trans-retinal to enter the visual cycle. The pathogenesis of diseases caused by mutations in ABCA4 is complex, comprising a loss-of-function component as well as photoreceptor stress caused by protein mislocalization and misfolding.


Retinal Pigment Epithelium Cytoplasmic Side Retinal Pigment Epithelium Disk Membrane Retinal Pigment Epithelium Cell 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



This work was supported by the National Institutes of Health (NIH grants EY09339, P30 EY11373, and EY08123). We thank members of the Palczewski laboratory for their helpful comments.


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© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  • Yaroslav Tsybovsky
    • 1
  • Robert S. Molday
  • Krzysztof Palczewski
  1. 1.Department of PharmacologyCase Western Reserve UniversityClevelandUSA

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