Panel a: From sequence analysis it is apparent that the VHDL receptor (red) is unlike a classical receptor of receptor mediated endocytosis, which bind its ligand VHDL (green) but also intracellular components like clathrin (blue).
Panel b: It is possible, but less likely, that the VHDL receptor acts as an intermediary link between storage proteins (green circle) and a different, yet unknown receptor (black).
Panel c: Since massive phagocytosis takes place in insect fat body prior to pupation, selective uptake can be achieved without intracellular contacts. As long as the receptor remains bound to the plasma membrane, its ligands will become enriched at the extracellular membrane surface and sequestered more efficiently than unbound hemolymph proteins.