The carboxyl-terminal domain is essential for rhodopsin transport in rod photoreceptors.

The role of the carboxyl-terminal domain in rhodopsin transport was investigated using transgenic mice expressing a rhodopsin truncation mutant lacking the terminal 15 amino acids (S334ter). It was previously shown that S334ter translocates to the outer segment in the presence of endogenous rhodopsin. We now show that in the absence of endogenous rhodopsin S334ter mis-localizes to the plasma membrane and fails to reconstitute outer segment structures. Surprisingly, this mis-localization does not affect photoreceptor cell survival. These results provide further evidence on the important role of the COOH-terminal domain in rhodopsin trafficking and demonstrate an absolute requirement of this domain for correct vectorial transport of rhodopsin in rod photoreceptors.