ATP-binding cassette, sub-family B member 11 (ABCB11), also known as the bile salt export pump (BSEP), is a protein which in humans is encoded by the ABCB11gene.[5]
Function
The product of the ABCB11 gene is an ABC transporter named BSEP (bile salt export pump), or sPgp (sister of P-glycoprotein). This membrane-associated protein is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White).[6]
This protein is a member of the MDR/TAP subfamily. Some members of the MDR/TAP subfamily are involved in multidrug resistance. This particular protein is responsible for the transport of taurocholate and other cholate conjugates from hepatocytes (liver cells) to the bile. In humans, the activity of this transporter is the major determinant of bile formation and bile flow.[7][8][9][10]
Bile salts from the cytoplasm of hepatocytes are transported by the bile salt export pump (BSEP) into bile canaliculi. When bile salt export is deficient due to mutation in the ABCB11 gene, this can lead to intrahepatic toxic accumulation of the bile salts. Individuals with such mutations have an increased incidence of hepatocellular carcinoma or cholangiocarcinoma.[16]
^Zinchuk VS, Okada T, Akimaru K, Seguchi H (March 2002). "Asynchronous expression and colocalization of Bsep and Mrp2 during development of rat liver". American Journal of Physiology. Gastrointestinal and Liver Physiology. 282 (3): G540–G548. doi:10.1152/ajpgi.00405.2001. PMID11842005.
^Noe J, Kullak-Ublick GA, Jochum W, Stieger B, Kerb R, Haberl M, et al. (September 2005). "Impaired expression and function of the bile salt export pump due to three novel ABCB11 mutations in intrahepatic cholestasis". Journal of Hepatology. 43 (3): 536–543. doi:10.1016/j.jhep.2005.05.020. PMID16039748.
^Knisely AS, Strautnieks SS, Meier Y, Stieger B, Byrne JA, Portmann BC, et al. (August 2006). "Hepatocellular carcinoma in ten children under five years of age with bile salt export pump deficiency". Hepatology. 44 (2): 478–486. doi:10.1002/hep.21287. PMID16871584. S2CID22994215.
Dixon PH, van Mil SW, Chambers J, Strautnieks S, Thompson RJ, Lammert F, et al. (April 2009). "Contribution of variant alleles of ABCB11 to susceptibility to intrahepatic cholestasis of pregnancy". Gut. 58 (4): 537–544. doi:10.1136/gut.2008.159541. PMID18987030. S2CID206948058.
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Chen HL, Liu YJ, Su YN, Wang NY, Wu SH, Ni YH, et al. (December 2008). "Diagnosis of BSEP/ABCB11 mutations in Asian patients with cholestasis using denaturing high performance liquid chromatography". The Journal of Pediatrics. 153 (6): 825–832. doi:10.1016/j.jpeds.2008.06.034. PMID18692205.
Thompson R, Strautnieks S (November 2001). "BSEP: function and role in progressive familial intrahepatic cholestasis". Seminars in Liver Disease. 21 (4): 545–550. doi:10.1055/s-2001-19038. PMID11745042. S2CID36313859.
Kim SR, Saito Y, Itoda M, Maekawa K, Kawamoto M, Kamatani N, et al. (2009). "Genetic variations of the ABC transporter gene ABCB11 encoding the human bile salt export pump (BSEP) in a Japanese population". Drug Metabolism and Pharmacokinetics. 24 (3): 277–281. doi:10.2133/dmpk.24.277. PMID19571440.
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