The tetraspanin disc proteins, peripherin-2 and ROM1, facilitate CNG channel localization to the rod outer segment

The light-responsive outer segment of rod photoreceptors is composed of two distinct membrane subdomains: discs and the plasma membrane. We investigate how the disc protein peripherin-2 is engaged in CNG channel delivery to the outer segment. Instead of forming outer segments, peripherin-2 knockout (Rds-/-) photoreceptors release ciliary ectosomes, in which CNG channel levels are markedly reduced relative to other outer segment proteins. This is intriguing as downregulation of the CNG channel is not a general feature of degenerative mouse models with dysmorphic outer segments. Overexpression of the {beta}1-subunit of CNG in Rds-/- rods reveals that the majority is trapped in intracellular me