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). Interacts with STX3 (By similarity). Interacts with clathrin (By similarity). Expressed in circumvallate papillae and testis (PubMed:16720576). Expressed in the retina. Isoform 1 is predominantly present in mature optic cups. Isoform 1 expression is confined to the cell body and inner segment of developing rod photoreceptor cells (PubMed:27889058). The disease is caused by variants affecting the gene represented in this entry. Belongs to the DP1 family.