sentences:  It is believed that the intracellular transport of the nascent protein depends, to some extent, on the oligomerization of Env precursors, which allows hydrophobic sequences to be buried inside the protein structure.This oligomerization has also been implicated in fusion initiation with the membrane of the target cell.Env can be modified by the addition of mannose-rich oligosaccharides, a process that takes place in the rough endoplasmic reticulum and is carried out by the enzymes of the host cell.