FunctionRequired for normal development of photoreceptor synapses. Required for normal photoreceptor function and for long-term survival of photoreceptor cells. Interacts with cytoskeleton proteins and may play a role in protein transport in photoreceptor cells (By similarity). Binds lipids, especially phosphatidylinositol 3-phosphate, phosphatidylinositol 4-phosphate, phosphatidylinositol 5-phosphate, phosphatidylinositol 3,4-bisphosphate, phosphatidylinositol 4,5-bisphosphate, phosphatidylinositol 3,4,5-bisphosphate, phosphatidylserine and phosphatidic acid (in vitro). Contribute to stimulation of phagocytosis of apoptotic retinal pigment epithelium (RPE) cells and macrophages.
Involvement in diseaseDefects in TULP1 are the cause of retinitis pigmentosa type 14 (RP14) [MIM:600132]. RP leads to degeneration of retinal photoreceptor cells. Patients typically have night vision blindness and loss of midperipheral visual field. As their condition progresses, they lose their far peripheral visual field and eventually central vision as well. RP14 inheritance is autosomal recessive. Defects in TULP1 are the cause of Leber congenital amaurosis type 15 (LCA15) [MIM:613843]. LCA15 is a severe dystrophy of the retina, typically becoming evident in the first years of life. Visual function is usually poor and often accompanied by nystagmus, sluggish or near-absent pupillary responses, photophobia, high hyperopia and keratoconus.
Sequence similaritiesBelongs to the TUB family.
Cellular localizationCytoplasm. Cell membrane. Secreted. Cell junction > synapse. Detected at synapses between photoreceptor cells and second-order neurons. Does not have a cleavable signal peptide and is secreted by an alternative pathway.