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Xiao-Ming Zhang, Bret Hughes; Expression And Localization Of KCNQ5/Kv7.5 K+ Channels In Macaque Neural Retina And RPE. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3348.
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We have shown previously that adult human and monkey RPE cells exhibit an M-type K+ current that is active in the physiological voltage range. We have also shown that primate RPE and neural retina express transcript for the KCNQ5/Kv7.5 channel, which contributes to M-type channels in other cell types. The purpose of this study was to determine the expression and localization of KCNQ5 protein in monkey RPE and neural retina.
KCNQ expression was examined by Western analysis using membrane proteins from monkey RPE, neural retina, and skeletal muscle (positive control tissue) in conjunction with a rabbit anti-KCNQ5 antibody. KCNQ5 protein was localized in frozen sections of monkey retina by immunofluorescence confocal microscopy using the same anti-KCNQ5 antibody.
We detected an appropriately-sized band corresponding to KCNQ5 in Western blots of RPE, neural retina, and skeletal muscle proteins. Punctate and diffuse KCNQ5 immunoreactivity was found near the RPE basal membrane. KCNQ5 immunoreactivity was also observed in the inner segments of rod and cone photoreceptors and in retinal blood vessels. KCNQ5 immunoreactivity was eliminated in both Western blots and retinal sections when the anti-KCNQ5 antibody was pre-absorbed with antigenic peptide.
The results suggest that KCNQ5 channels are expressed in the basal membrane of the RPE, where they may contribute to K+ channels involved in active K+ absorption. KCNQ5 channels also appear to be expressed in the inner segments of rod and cone photoreceptors, where they may help set the membrane potential and shape the photoresponse.
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