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Cecilia Gerstner, Houbin Zhang, Jeanne Frederick, Wolfgang Baehr; UNC119B, an UNC119/RG4 paralog expressed in retina and RPE. Invest. Ophthalmol. Vis. Sci. 2013;54(15):697.
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© ARVO (1962-2015); The Authors (2016-present)
UNC119B is related closely to UNC119/HRG4, a homolog of C. elegans Unc-119, and more distantly to the prenyl-binding protein, PrBP/δ. Each of these (UNC119, UNC119B and PrBP/δ) forms an immunoglobulin-like β-sandwich fold for lipid binding. Our purpose was to identify expression and function of the UNC119B isoform in retina and RPE.
GST-pulldowns, preparation of monospecific antibodies raised in rabbit and chicken, western blotting, immunohistochemistry, generation of an Unc119b knockout mouse.
By gene and EST blasting, UNC119B was determined to be expressed in both vertebrates and invertebrates. Polyclonal antibodies were generated using N-terminal peptide and recombinant full-length UNC119B as antigens. By multiple mouse tissue immunoblot, we show that UNC119B is expressed strongly in testis, ovary, lung, brain and thymus, but weakly in whole eye, heart and muscle. UNC119B is expressed prominently in the RPE and weakly in retina. Immunohistochemistry using frozen mouse and monkey (Macaca mulatta) retina/RPE sections show partial colocalization with RDH5 in RPE cell peripheral margins. Both GST-UNC119B and GST-UNC119/RG4 pull down Tα from retina lysates, suggesting closely-related functions as acyl binding proteins. Both UNC119 isoforms reveal perfect conservation of all amino acids known to interact with the acyl side chain and N-terminal residues of Tα, and predict nearly identical structures. An Unc119b-/- mouse was generated using a MMRCC (UC Davis) genetrap. The trap, located in exon3, blocks UNC119B protein expression. The Unc119b-/- mouse did not reveal a retina degeneration phenotype at one-month postnatally.
UNC119B is detected prominently in the RPE and weakly in the retina. UNC119B may function as an acyl binding protein with specificity for a novel G protein α-subunit expressed in the RPE.
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