Multidrug resistance-associated protein 2 (MRP2) also called canalicular multispecific organic anion transporter 1 (cMOAT) or ATP-binding cassette sub-family C member 2 (ABCC2) 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 ...

that in humans is encoded by the ''ABCC2''

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

MRP2 is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-

cellular membrane The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extra ...

s. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). More specifically, this protein is a member of the MRP subfamily, which is involved in multi-drug resistance. This protein is expressed in the canalicular (apical) part of the

hepatocyte A hepatocyte is a cell of the main parenchymal tissue of the liver. Hepatocytes make up 80% of the liver's mass. These cells are involved in: * Protein synthesis * Protein storage * Transformation of carbohydrates * Synthesis of cholesterol, bi ...

and functions in biliary transport. Substrates include

anticancer drug Chemotherapy (often abbreviated chemo, sometimes CTX and CTx) is the type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic agents or alkylating agents) in a standard regimen. Chemotherapy may be given with a cu ...

s such as

vinblastine Vinblastine, sold under the brand name Velban among others, is a chemotherapy medication, typically used with other medications, to treat a number of types of cancer. This includes Hodgkin's lymphoma, non-small-cell lung cancer, bladder canc ...

; therefore, this protein appears to contribute to drug resistance in mammalian cells. MRP2 is also expressed in the

apical membrane The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extra ...

proximal renal tubule The proximal tubule is the segment of the nephron in kidneys which begins from the renal (tubular) pole of the Bowman's capsule to the beginning of loop of Henle. At this location, the glomerular parietal epithelial cells (PECs) lining bowman’s ...

endothelial cells The endothelium (: endothelia) is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the res ...

where they are involved in the excretion of small organic anions.

MRP2 inhibitors

Clinical significance

Dubin–Johnson syndrome

Several different mutations in this gene have been observed in patients with

Dubin–Johnson syndrome Dubin–Johnson syndrome is a rare, autosomal recessive, benign disorder that causes an isolated increase of conjugated bilirubin in the serum. Classically, the condition causes a black liver due to the deposition of a pigment similar to melanin ...

(DJS), an autosomal recessive disorder characterized by conjugated hyperbilirubinemia.

Iatrogenic Fanconi syndrome

Many negatively charged metabolic waste products are eliminated from the body by the kidneys. These organic anions are transported from the blood into the

endothelial The endothelium (: endothelia) is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the res ...

cells of the renal proximal tubules by the OAT1 transporter. From there, these waste

molecules A molecule is a group of two or more atoms that are held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemistry ...

are transported into the lumen of the tubule by the MRP2 transporter. Many drugs are eliminated from the body by this mechanism. Some of these drugs pass through the MRP2 transporter slowly. This may cause a buildup of organic anions in 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 the cells. Drugs that inhibit the MRP2 transporter can cause a buildup of organic anions inside renal proximal tubule cells. If some of these organic anions inhibit mitochondrial DNA synthesis, it may cause iatrogenic Fanconi syndrome. The nucleoside phosphonate

adefovir Adefovir is a prescription medicine used to treat (chronic) infections with hepatitis B virus. A prodrug form of adefovir was previously called bis-POM PMEA, with trade names Preveon and Hepsera. It is an orally administered nucleotide analog re ...

is a MRP2 inhibitor that has been linked to kidney disease.

Tenofovir Tenofovir disoproxil, sold under the brand name Viread among others, is a medication used to treat chronic hepatitis B and to prevent and treat HIV/AIDS. It is generally recommended for use with other antiretrovirals. It may be used for pr ...

and

cidofovir Cidofovir, brand name Vistide, is a topical or injectable antiviral medication primarily used as a treatment for cytomegalovirus (CMV) retinitis (an infection of the retina of the eye) in people with AIDS. Cidofovir was approved for medical ...

are also nucleoside phosphonates that inhibit MRP2 and have been associated with Fanconi syndrome.

Interactive pathway map

References

External links

* {{DEFAULTSORT:Abcc2 ATP-binding cassette transporters