Sandbox Reserved 1769: Difference between revisions

Sodium-taurocholate Co-transporting Polypeptide (NTCP) is a member of the solute carrier membrane transport protein family. It is found within the membrane of [[Image:Bile Salt.png|200 px|right|thumb|Figure 1. Structure of Cholic Acid, an example of a bile acid.]][https://en.wikipedia.org/wiki/Hepatocyte hepatocytes], and its primary role is to facilitate the transport of [https://en.wikipedia.org/wiki/Bile_acid bile salts] into hepatocytes from the bloodstream (Fig. 1).<Ref name="Goutam"> Goutam K, Ielasi FS, Pardon E, Steyaert J, Reyes N. Structural basis of sodium-dependent bile salt uptake into the liver. Nature. 2022 Jun;606(7916):1015-1020. [https://dx.doi.org/10.1038/s41586-022-04723-z DOI: 10.1038/s41586-022-04723-z]. </Ref> This is important because 90% of human bile salts  are recycled daily, so the function of NTCP is critical in providing bile acids to solubilize fats for digestion. In addition to transporting bile acids into the cytoplasm of hepatocytes (Figure 2), NTCP also serves as an entry point receptor for [https://en.wikipedia.org/wiki/Hepatitis_B Hepatitis B (HBV)] and [https://en.wikipedia.org/wiki/Hepatitis_D Hepatitis D (HDV)] viruses.<Ref name="Asami"> Asami J, Kimura KT, Fujita-Fujiharu Y, Ishida H, Zhang Z, Nomura Y, Liu K, Uemura T, Sato Y, Ono M, Yamamoto M, Noda T, Shigematsu H, Drew D, Iwata S, Shimizu T, Nomura N, Ohto U. Structure of the bile acid transporter and HBV receptor NTCP. Nature. 2022 Jun; 606 (7916):1021-1026. [https://dx.doi.org/10.1038/s41586-022-04845-4 DOI: 10.1038/s41586-022-04845-4]. </Ref> [[Image:Ntcpmech.jpg|400 px|thumb|Figure 2. Overall NTCP mechanism of both bile acid transport and hepatitis virus cellular entry.]]

NTCP contains <scene name='95/952697/Ntcp_open-pore_state/16'>two characteristic domains</scene>: the core and panel domains (Figure 3). Movement of these two domains allows recognition and transport of bile acids into hepatocytes.  

**Formed by the packing of a helix bundle of *<b><font color="dark blue">TM2, TM3, and TM4</font></b>: with another helix bundle of TM7, TM8, and TM9. These two helix bundles are related by pseudo two-fold symmetry.<Ref name="Qi"> Qi X, Li W. Unlocking the secrets to human NTCP structure. Innovation (Camb). 2022 Aug 1;3(5):100294. [https://dx.doi.org/10.1016/j.xinn.2022.100294 DOI: 10.1016/j.xinn.2022.100294]. </Ref>