Required for correct function and survival of retinal photoreceptors (PubMed:27889058). Required for retinal development (By similarity). In rod photoreceptors, facilitates stability and/or trafficking of guanylate cyclases and is required to maintain endoplasmic reticulum and mitochondrial homeostasis (By similarity). May play a role in clathrin-coated intracellular vesicle trafficking of proteins from the endoplasmic reticulum to the retinal rod plasma membrane (By similarity). {ECO:0000250|UniProtKB:Q9JM62, ECO:0000269|PubMed:27889058}. This is the function of ENSG00000115255 (REEP6, receptor accessory protein 6).