ATP-binding cassette, sub-family B member 11 (ABCB11), also known as the bile salt export pump (BSEP), is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
which in humans is encoded by the
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.
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).
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
Bile (from Latin ''bilis''), also known as gall, is a yellow-green/misty green fluid produced by the liver of most vertebrates that aids the digestion of lipids in the small intestine. In humans, bile is primarily composed of water, is pro ...
. In humans, the activity of this transporter is the major determinant of bile formation and bile flow.
Clinical significance
''ABCB11'' is a gene associated with
progressive familial intrahepatic cholestasis type 2 (PFIC2).
PFIC2 caused by mutations in the ''ABCB11'' gene increases the risk of
hepatocellular carcinoma in early life.
(BRIC) is associated with episodic cholestatic jaundice and mutations in ''
ATP8B1'' or ''ABCB11''.
s from the
cytoplasm
The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell a ...
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.
References
Further reading
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External links
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{{DEFAULTSORT:Abcb11