The invention provides a transgene construct consisting of a transgene
encoding a membrane polypeptide comprising a rod outer segment (ROS)
targeting signal, and an operably associated species specific
rod-specific regulatory sequence, wherein said polypeptide is not
rhodopsin. The membrane polypeptide can be a G protein-coupled receptor
(GPCR). Transgenic membrane polypeptides include a receptor selected from
5HT.sub.1A, 5HT.sub.1B, 5HT.sub.1D, 5HT.sub.1E, 5HT.sub.1F, 5HT.sub.2A,
5HT.sub.2B, 5HT.sub.2C, 5HT.sub.4A, 5HT.sub.5A, 5HT.sub.6, 5HT.sub.7A,
EDG1, EDG2, EDG3, EDG4, EDG5, EDG6, EDG7, EDG8, CB2, FMLP and MC4. The
invention also provides a Xenopus cell whose genome contains a transgene
encoding a membrane polypeptide comprising a ROS targeting signal
operably associated with a Xenopus rod-specific regulatory sequence,
wherein said polypeptide is not a rhodopsin. A Xenopus tadpole or adult
whose genome contains a transgene encoding a membrane polypeptide
comprising a ROS targeting signal operably associated with a Xenopus
rod-specific regulatory sequence, wherein said polypeptide is not a
rhodopsin is further provided.
