FIG 2.

Bile salts blocked the interaction between the pre-S1 peptide and NTCP. (A) Inhibition of FITC-conjugated pre-S1 peptide binding by different bile salts. FITC–pre-S1 peptide (400 nM) was incubated with NTCP-transfected HepG2 cells for 1 h in the presence of the indicated bile salt (20 μM). The binding efficiency of the pre-S1 peptide was analyzed via a fluorescence microscope. CA, cholic acid; GCA, glycocholic acid; LCA, lithocholic acid; DCA, deoxycholic acid; TCA, taurocholic acid; TLCA, taurolithocholic acid; CDCA, chenodeoxycholic acid; UDCA, ursodeoxycholic acid; HDCA, hyodeoxycholic acid; TUDCA, tauroursodeoxycholic acid. (B) Competition for [³H]taurocholate uptake by other bile salts. The indicated bile salts (at 10 μM or 20 μM) were examined. Uptake efficiency is presented as the percent uptake compared with the dimethyl sulfoxide group. (C) The ability of TUDCA to inhibit [³H]taurocholate uptake by HepG2-NTCP cells. TUDCA at the indicated concentration was present in the medium during the entire [³H]taurocholate uptake process.