Steroline

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Sterolin-1, ABCG5
Properties of human protein
Mass / length primary structure 651 amino acids
Secondary to quaternary structure multipass membrane protein, heterodimer
Identifier
Gene name ABCG5
External IDs
Transporter classification
TCDB 3.A.1.204.5
designation ABC transporter

Sterolin-2, ABCG8
Properties of human protein
Mass / length primary structure 673 amino acids
Secondary to quaternary structure multipass membrane protein, heterodimer
Isoforms 2
Identifier
Gene name ABCG8
External IDs
Transporter classification
TCDB 3.A.1.204.5
designation ABC transporter

Sterolin (ABCG5 / G8 efflux pump) is the cell membrane - protein , which in mammals excess cholesterol and phytosterols from liver cells pumps out, after which these substances in the gallbladder flow. To a lesser extent, steroline is found in the membrane of enterocytes of the intestine . The energy for the pumping process is provided by ATP . Sterolin is therefore a membrane-bound ATPase , more precisely an ABC transporter .

Steroline is a heterodimer made up of the two semi-transporters ABCG5 and ABCG8. Mutations in either of the two genes can impair the function of sterolins and lead to (rare, hereditary) sitosterinemia . Other mutations increase pump activity and lead to an increased risk of gallstones (GBD4).

The transport equation for ABC transporters (Efflux):

Substrate (inside) + ATP ⇒ substrate (outside) + ADP + P i

In a study with Chileans, a variant of ABCG5 was associated with hypercholesterolemia . A Taiwanese study showed a similar association with a variant of ABCG8.

Individual evidence

  1. ↑ Kidambi S, Patel SB: Cholesterol and non-cholesterol sterol transporters: ABCG5, ABCG8 and NPC1L1: a review . In: Xenobiotica . 38, No. 7-8, July 2008, pp. 1119-39. doi : 10.1080 / 00498250802007930 . PMID 18668442 .
  2. ↑ UniProt Q9H222 , UniProt Q9H221
  3. ↑ Caamaño JM, Pacheco A, Lanas F, Salazar LA: Single nucleotide polymorphisms in ABCG5 and ABCG8 genes in Chilean subjects with polygenic hypercholesterolemia and controls . In: Clin. Chem. Lab. Med. . 46, No. 11, 2008, pp. 1581-5. doi : 10.1515 / CCLM.2008.311 . PMID 19012522 .
  4. ↑ Chen ZC, Shin SJ, Kuo KK, Lin KD, Yu ML, Hsiao PJ: Significant association of ABCG8: D19H gene polymorphism with hypercholesterolemia and insulin resistance . In: J. Hum. Genet. . 53, No. 8, 2008, pp. 757-63. doi : 10.1007 / s10038-008-0310-2 . PMID 18581044 .
  5. ↑ Rudkowska I, Jones PJ: Polymorphisms in ABCG5 / G8 transporters linked to hypercholesterolemia and gallstone disease . In: Nutr. Rev. . 66, No. 6, June 2008, pp. 343-8. doi : 10.1111 / j.1753-4887.2008.00042.x . PMID 18522623 .

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