Site-directed mutagenesis of the inhibitory subunit of retinal rod cyclic GMP phosphodiesterase.

In order to study the role of individual amino acids in the function of the inhibitory subunit, gamma, of retinal rod phosphodiesterase (PDE), the following substitutions were made: Arg-24----Gly, Lys-29----Thr, Arg-33----Gly, Lys-39----Thr, Lys-41----Thr, Lys-44----Thr, Lys-45----Thr, Glu-77----Gly, and Tyr-84----Ala. Deletion of seven C-terminal amino acids (delta 81-87) was also investigated, and the activity of all the mutant PDE gamma forms determined. Expression of the mutant PDE gamma genes was achieved by sequential in vitro transcription and translation.