SLC10A1 and viral infectious disease: We then assessed whether these 54 amino acids are involved in 1) supporting viral infection, 2) mediating preS1 binding, and 3) bile acid uptake, as well as 4) cell surface expression in the following analysis: We constructed the plasmids encoding the NTCP carrying an alanine mutation at these 54 amino acids and overexpressed these NTCP mutants or the wild type in HepG2 cells (which do not originally express endogenous NTCP) to document the functions listed above.