Binds negatively charged membrane lipids, such as phosphatidylserine and phosphoinositides (By similarity). May play a role in cell-cell adhesion processes in the retina, via homomeric interaction between octamers present on the surface of two neighboring cells (PubMed:27114531). Required for normal structure and function of the retina (PubMed:19093009). Homooctamer of 4 homodimers; disulfide-linked (PubMed:15644328, PubMed:19849666). The homooctamer has a flat, cogwheel structure with a diameter of about 14 nm (PubMed:27798099, PubMed:26812435, PubMed:27114531). Two stacked octamers can assemble to form a hexadecamer (PubMed:27798099, PubMed:26812435, PubMed:27114531). Binds to phosphatidylserine-containing lipid membranes and embeds itself partially into the lipid bilayer. Lipid-binding requires the presence of Ca(2+) ions. Restricted to the retina (at protein level) (PubMed:10915776). Detected in the inner segment of the photoreceptors, the inner nuclear layer, the inner plexiform layer and the ganglion cell layer (at protein level). At the macula, expressed in both the outer and inner nuclear layers and in the inner plexiform layer (at protein level) (PubMed:10915776). Detected in retina (PubMed:9326935). Detected only within the photoreceptor cell layer, most prominently within the inner segments of the photoreceptors (PubMed:10915776). Undetectable in the inner plexiform layers and the inner nuclear layer (PubMed:10915776). Up-regulated during the differentiation of a retinoblastoma cell line. The disease is caused by variants affecting the gene represented in this entry. Retina International's Scientific Newsletter