A cis-acting element, T alpha-1, in the upstream region of rod alpha-transducin gene that binds a developmentally...

The G protein transducin (T) is an integral component of the signal transduction pathway in photoreceptors. We have identified a cis-acting element, T alpha-1, in the upstream region of the mouse rod alpha-T (Tr alpha) gene that may be important for tissue-specific expression. T alpha-1 binds a retina-specific nuclear factor of apparent molecular mass of 90 kDa. Binding to the T alpha-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 Tr alpha gene expression. The sequence of T alpha-1 shows homology with RET-1, a cis-acting element in the proximal promoter of opsin gene that binds a distinct retina-specific factor. T alpha-1 and RET-1 sequences may have been derived from a prototype T alpha-1/RET-1 sequence, evolved to confer photoreceptor specificity on retina-specific genes.