The intracellular role of placental protein 17b (PP17b)/ TIP47has been controversial, because it is considered tobe a protein required for mannose 6-phosphate receptor trans-port from endosome totrans-Golgi as well as a neutral lipid similaritybetween theamino acid sequences of PP17 variants, adipophilin and perilipins, andbetween their gene structures indicate that PP17baswell as other alternatively spliced PP17 variants belong to the lipid storage droplet protein family, containing also some differentiation factors
