Purchase this article with an account.
M.E. Cheetham, C. Grayson, J.P. Chapple, A.J. Hardcastle; The X-Linked Retinitis Pigmentosa Protein RP2 Links the Plasma Membrane and the Cytoskeleton . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1531.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Mutations in RP2 cause up to 20% of X-linked retinitis pigmentosa. RP2 is a ubiquitously expressed protein of unknown function. To further define the possible cellular functions of RP2 we have investigated the localization of the protein and its interacting partner, Arl3, in human retina. The organization of RP2 on the plasma membrane was delineated and the relationship between RP2 and Arl3 with the cytoskeleton explored. Methods: RP2 and Arl3 expression were detected in paraffin and agarose embedded adult human retinae. Their localization was compared to a range of marker proteins. The organization of RP2 on membranes was probed by immunocytochemistry of polarized epithelial cells. Detergent resistant membranes (DRMs) were prepared from SH-SY5Y cells and the presence of RP2 and Arl3 in detergent resistant fractions determined by western blotting. The association of RP2 and Arl3 with the cytoskeleton were investigated by immunocytochemistry and co-sedimentation. Results: RP2 was localized to the plasma membrane of cells throughout the retina, including both rod and cone photoreceptors where plasma membrane staining extended from the outer segment through the inner segment to the synaptic terminals. No enrichment of RP2 staining was observed in any photoreceptor organelle. In polarized epithelial cells in culture and in vivo RP2 was present in both the apical and basolateral domains of the plasma membrane. However, a significant proportion of RP2 in cultured neuroblastoma cells was associated with DRMs, indicating that RP2 is a lipid raft associated protein. Arl3 was not present in DRMs but decorated microtubule structures in the retina, in particular the connecting cilium, and co-purified with microtubules and tubulin. Conclusions: RP2 localized to the plasma membrane of photoreceptors. Within the plasma membrane, RP2 is associated with DRMs that are enriched in signaling complexes. Arl3 did not associate with DRMs but behaved as a microtubule associated protein MAP. These data indicate that RP2 may co-operate with its interacting partner Arl3 to link plasma membrane signaling complexes to the cytoskeleton.
This PDF is available to Subscribers Only