Cellular retinaldehyde-binding protein interacts with ERM-binding phosphoprotein 50 in retinal pigment epithelium.
PURPOSE: To characterize mechanisms of apical localization of visual cycle components in retinal pigment epithelium (RPE) by the identification of cellular retinaldehyde-binding protein ( CRALBP) interaction partners. METHODS: An overlay assay was used to detect interactions of CRALBP with components of RPE microsomes. Interacting proteins were identified with two-dimensional (2D)-PAGE and liquid chromatography tandem mass spectrometry (LC MS/MS). Protein interactions were characterized by affinity chromatography, peptide competition, and expression of protein domains. Protein colocalization in mouse retina was examined using double-label immunocytochemistry and confocal microscopy. RESULTS: CRALBP bound to a 54-kDa protein in RPE microsomes, which was identified as ERM ( ezrin, radixin, moesin)-binding phosphoprotein 50 ( EBP50), a PDZ domain protein, also known as sodium/hydrogen exchanger regulatory factory type 1 ( NHERF-1). EBP50 and ezrin in solubilized microsomes bound to CRALBP-agarose but not to a control agarose column. CRALBP bound to both recombinant PDZ domains of EBP50 but not to the C-terminal ezrin-binding domain. In outer retina, EBP50 and ezrin were localized to RPE and Müller apical processes. CRALBP was distributed throughout both RPE and Müller cells, including their apical processes. CONCLUSION: RM proteins are multivalent linkers that connect plasma membrane proteins with the cortical actin cytoskeleton. EBP50 interacts with ERM family members through a C-terminal domain and binds targets such as CRALBP through its PDZ domains, thus contributing to an apical localization of target proteins. Our results provide a structural basis for apical localization of a retinoid-processing complex in RPE cells and offer insight into the cell biology of retinoid processing and trafficking in RPE.[1]References
- Cellular retinaldehyde-binding protein interacts with ERM-binding phosphoprotein 50 in retinal pigment epithelium. Nawrot, M., West, K., Huang, J., Possin, D.E., Bretscher, A., Crabb, J.W., Saari, J.C. Invest. Ophthalmol. Vis. Sci. (2004) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg
