Constitutes the major component of lipophorin, which mediates transport for various types of lipids in hemolymph. Acts by forming lipoprotein particles that bind lipoproteins and lipids. Also involved in the transport of hydrophobic ligands like juvenile hormones, pheromone hydrocarbons and carotenoids. Required for morphogens wingless (wg) and hedgehog (hh) function, probably by acting as vehicles for the movement of wg and hh, explaining how covalently lipidated wg and hh can spread over long distances. May also be involved in transport and/or metabolism of heme. Secreted in hemolymph. During stage 12, it is highly present throughout the yolk sac. By late stage 14, it localizes in the lateral fat body cells. Starting at stage 14, it localizes to the apodemes. Component of hemolymph clots (at protein level). Expressed in the amniosera. May be modified covalently by lipidation. Cleaved into 2 chains by furin protease. However, prevention of cleavage does not impair its function (By similarity).