The g-subunit of the rod photoreceptor cGMP-binding cGMP-specific PDE is expressed in mouse lung

The type 6 phosphodiesterase (PDE-6) from retinal rod photoreceptors is an abg[in2] heterotetramer. The a-and b-subunits contain catalytic sites for cGMP hydrolysis, whereas the g-subunits (Pg) serve as a protein inhibitor of the enzyme. Pg is believed to be expressed only in photoreceptors. Using RT-PCR, we have amplified the complete coding sequence for Pg from mouse lung RNA. The expression of Pg in this tissue may be related to its ability to interact the type 5 phosphodiesterase (PDE-5), which is the predominant cGMP binding protein in lung. We therefore suggest that Pg may have a wider signaling role in mammalian cells than previousl y appreciated.