Rapid Communication: A cis‐Acting Element, Tα‐1, in the Upstream Region of Rod α‐Transducin Gene that Binds a Developmentally Regulated Retina‐Specific Nuclear Factor

Abstract: The G protein transducin (T) is an integral component of the signal transduction pathway in photoreceptors. We have identified a cis‐acting element, Ta‐1, in the upstream region of the mouse rod a‐T (T_rα) gene that may be important for tissue‐specific expression. Tα‐1 binds a retina‐specific nuclear factor of apparent molecular mass of 90 kDa. Binding to the Tα‐1 site is developmentally regulated and peaks between postnatal days 6 and 9. This corresponds to the time of rod photoreceptor maturation and the rise in T_rα gene expression. The sequence of Tα‐1 shows homology with RET‐1, a cis‐acting element in the proximal promoter of opsin gene that binds a distinct retina‐specific factor. Tα‐1 and RET‐1 sequences may have been derived from a prototype Tα‐1/RET‐1 sequence, evolved to confer photoreceptor specificity on retina‐specific genes.