The transgene expresses mouse Rho in which phosphorylating serines 334, 338 and 343 have been converted to inactivating alanines. Threonine-associated phosphorylation sites (T336, T340 and T342) remain functional. An A337V mutation was introduced to confer a linear epitope for mAb3A6, that allows specific recognition of transgenic versus endogenous opsin. (J:221472)