Mediates the intracellular transfer of ceramide-1-phosphate (C1P) between organelle membranes and the cell membrane. Required for normal structure of the Golgi stacks. Can bind phosphoceramides with a variety of aliphatic chains, but has a preference for lipids with saturated C16:0 or monounsaturated C18:1 aliphatic chains, and is inefficient with phosphoceramides containing lignoceryl (C24:0). Plays a role in the regulation of the cellular levels of ceramide-1-phosphate, and thereby contributes to the regulation of phospholipase PLA2G4A activity and the release of arachidonic acid. Has no activity with galactosylceramide, lactosylceramide, sphingomyelin, phosphatidylcholine, phosphatidic acid and ceramide. C1P transfer is stimulated by phosphatidylserine in C1P source vesicles (By similarity). Regulates autophagy, inflammasome mediated IL1B and IL18 processing, and pyroptosis, but not apoptosis (PubMed:29164996). N-(hexadecanoyl)-sphing-4-enine-1-phosphate(in) = N-(hexadecanoyl)-sphing-4-enine-1-phosphate(out) N-(9Z-octadecenoyl)-sphing-4-enine-1-phosphate(in) = N-(9Z-octadecenoyl)-sphing-4-enine-1-phosphate(out) Belongs to the GLTP family.