Fig. 2.

Amino acid sequence alignment of SLC10A family members. The predicted nine transmembrane domains based on bacterial Slc10a-like genes are indicated in gray bars. Residues that directly interact with the two Na⁺ ions are highlighted. Residues whose mutations affect human NTCP binding activity with taurocholic acid appear in bold and are underlined (11). HuNTCP, human NTCP(NP_003040); RaNtcp, rat Ntcp(NP_058743); RtSlc10a1, rainbow trout Slc10a1(BAN81910); NmSlc10a, N. meningitidis Slc10a(3ZUY_A); YfSlc10a, Y. frederiksenii Slc10a(4N7W) are shown.