Martinez J A, Barnstable C J
Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, Connecticut, 06520, USA.
Biochem Biophys Res Commun. 1998 Sep 8;250(1):175-80. doi: 10.1006/bbrc.1998.9261.
Our previous studies on the transcriptional regulation of rod opsin gene expression had defined a strikingly conserved element, Ret 1/PCEI, present in the upstream regulatory regions of opsin and other photoreceptor-specific genes. This element interacts with a 40 kDa, developmentally regulated, retina-specific protein. In this study we report the cloning of the novel retina-specific homeodomain protein Erx. Erx contains a homeodomain that is 79% homologous to that of Drosophila empty spiracles. This 40 kDa protein can interact with the Ret 1 element in electrophoretic mobility shift assays. Mutation of key residues in Ret 1 eliminates all Erx binding. Transient transfection of Y79 retinobalstoma cells with Erx leads to significant transcriptional activation of a reporter gene via Ret 1 elements. We conclude that Erx is the Ret 1 binding activity. This is the first example of a Q50 homeodomain protein expressed in retinal photoreceptors.
我们之前关于视杆视蛋白基因表达转录调控的研究确定了一个高度保守的元件Ret 1/PCEI，它存在于视蛋白及其他光感受器特异性基因的上游调控区域。该元件与一种40 kDa、受发育调控的视网膜特异性蛋白相互作用。在本研究中，我们报告了新型视网膜特异性同源域蛋白Erx的克隆。Erx含有一个与果蝇空泡同源的同源域，同源性为79%。在电泳迁移率变动分析中，这种40 kDa的蛋白能与Ret 1元件相互作用。Ret 1中关键残基的突变消除了所有Erx结合。用Erx瞬时转染Y79视网膜母细胞瘤细胞可通过Ret 1元件导致报告基因的显著转录激活。我们得出结论，Erx就是Ret 1结合活性。这是在视网膜光感受器中表达的Q50同源域蛋白的首个例子。
