After uncoating, the vesicle can fuse with an early endosome. Proton pumps acidify the lumen of the endosome, and this may cause the fusion protein to be released from the receptor protein. Proteins present in the lumen of the endosome can then be delivered to late endosomes and subsequently to lysosomes. If the fusion protein does not dissociate from the receptor in the early endosome, both the fusion protein and receptor are likely to be taken to the lysosome. The most likely reason why the fusion proteins are taken up by hepatocytes and not by other cells is the cell specific expression of the receptor.
Cells differ in the receptors that they display on their surfaces.
So the scientists would be wise to choose a receptor that is present on liver cells. There are at least two possible reasons for the change in activity of the fusion proteins when they enter the cell. As the fusion protein travels from the blood to the lysosome, it encounters different pH conditions. The pH of the blood is approximately 7.35. We know that pH affects the folding of proteins.