1. Ankyrin-B is required for coordinated expression of beta-2-spectrin, the Na/K-ATPase and the Na/Ca exchanger in the inner segment of rod photoreceptors.
- Author
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Kizhatil K, Sandhu NK, Peachey NS, and Bennett V
- Subjects
- Animals, Ankyrins deficiency, Ankyrins metabolism, Electroretinography, Eye Proteins metabolism, Humans, Mice, Mice, Inbred C57BL, Retinal Photoreceptor Cell Inner Segment physiology, Species Specificity, Xenopus, Ankyrins physiology, Carrier Proteins metabolism, Microfilament Proteins metabolism, Retinal Photoreceptor Cell Inner Segment metabolism, Sodium-Calcium Exchanger metabolism, Sodium-Potassium-Exchanging ATPase metabolism
- Abstract
Rod photoreceptors are highly polarized cells whose exquisite sensitivity to light depends on precise compartmentalization of ion channels/transporters within specialized membrane domains. Here, we report evidence for an ankyrin-B based mechanism for coordinated expression of the beta-2-spectrin-based membrane skeleton, and the Na/K-ATPase and Na/Ca exchanger in the inner segment of rod photoreceptors. We first discovered that ankyrin-B localizes to the inner segments but not outer segments of rod photoreceptors in vertebrates including humans, mice, and frogs. We found that haploinsufficiency of ankyrin-B in mice is accompanied by 50% reduction in inner segments of membrane proteins, including the Na/K-ATPase and the Na/Ca exchanger, as well as beta-2-spectrin, which is a component of the spectrin-actin membrane skeleton. These results are consistent with a mechanism where ankyrin-B is required to restrict the Na/K-ATPase and Na/Ca exchanger to the inner segment of rod photoreceptors by tethering these membrane proteins to beta-2-spectrin.
- Published
- 2009
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