Sulfonylurea receptor

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ATP-binding cassette, sub-family C (CFTR/MRP), member 8
Identifiers
Symbol ABCC8
Alt. symbols SUR1
Entrez 6833
HUGO 59
OMIM 600509
RefSeq NM_000352
UniProt Q09428
Other data
Locus Chr. 11 p15.1
ATP-binding cassette, sub-family C (CFTR/MRP), member 9
Identifiers
Symbol ABCC9
Alt. symbols SUR2A, SUR2B
Entrez 10060
HUGO 60
OMIM 601439
RefSeq NM_005691
UniProt O60706
Other data
Locus Chr. 12 p12.1

In the field of molecular biology, the sulfonylurea receptors (SUR) are membrane proteins which are the molecular targets of the sulfonylurea class of antidiabetic drugs whose mechanism of action is to promote insulin release from pancreatic beta cells. More specifically, SUR proteins are subunits of the inward-rectifier potassium ion channels Kir6.x (6.1 and 6.2).[1] The association of four Kir6.x and four SUR subunits form an ion conducting channel commonly referred to as the KATP channel.

There are three forms of the sulfonylurea receptor, SUR1 encoded by the ABCC8 gene and SUR2A and SUR2B which are splice variants arising from a single ABCC9 gene.[2]

Function[edit]

The primary function of the sulfonylurea receptor is to sense intracellular levels of the nucleotides ATP and ADP and in response facilitate the open or closing its associated Kir6.x potassium channel. Hence the KATP channel monitors the energy balance within the cell.[3]

Depending on the tissue in which the KATP channel is expressed, altering the membrane potential can trigger a variety of down stream events. For example, in pancreatic beta cells, high levels of glucose lead to increased production of ATP which in turn binds to the KATP channel resulting in channel closure. The increase in membrane potential in turn opens voltage-dependent calcium channels increasing intracellular calcium concentrations which triggers exocytosis of insulin.

Under cerebral ischemic conditions SUR1, the regulatory subunit of the KATP- and the NCCa-ATP-channels, is expressed in neurons, astrocytes, oligodendrocytes, endothelial cells[4] and by reactive microglia.[5] SUR1 has been involved in improved outcome in animal stroke models by preventing brain swelling [6] and enhancing neuroprotection.[5]

Tissue distribution[edit]

The isoforms of the sulfonylurea receptor have the following tissue distribution:

Disease linkage[edit]

The SUR1 protein is coded by the ABCC8 gene and is associated with congenital hyperinsulinism[7] and susceptibility to type 2 diabetes.[8]

References[edit]

  1. ^ Campbell JD, Sansom MS, Ashcroft FM (2003). "Potassium channel regulation". EMBO Rep 4 (11): 1038–42. doi:10.1038/sj.embor.7400003. PMC 1326373. PMID 14593442. 
  2. ^ Aguilar-Bryan L, Clement JP 4th, Gonzalez G, Kunjilwar K, Babenko A, Bryan J (1 January 1998). "Toward understanding the assembly and structure of KATP channels". Physiol Rev 78 (1): 227–45. PMID 9457174. 
  3. ^ Nichols CG (2006). "KATP channels as molecular sensors of cellular metabolism". Nature 440 (7083): 470–6. doi:10.1038/nature04711. PMID 16554807. 
  4. ^ a b Simard JM, Woo SK, Schwartzbauer GT, Gerzanich V (June 2012). "Sulfonylurea receptor 1 in central nervous system injury: A focused review". J Cereb Blood Flow Metab 32 (9): 1699–1717. doi:10.1038/jcbfm.2012.91. PMC 3434627. PMID 22714048. 
  5. ^ a b c Ortega FJ, Gimeno-Bayon J, Espinosa-Parrilla JF, Carrasco JL, Batlle M, Pugliese M, Mahy N, Rodríguez MJ (May 2012). "ATP-dependent potassium channel blockade strengthens microglial neuroprotection after hypoxia-ischemia in rats". Exp Neurol 235 (1): 282–96. doi:10.1016/j.expneurol.2012.02.010. PMID 22387180. 
  6. ^ Simard JM, Chen M, Tarasov KV, Bhatta S, Ivanova S, Melnitchenko L, Tsymbalyuk N, West GA, Gerzanich V (Apr 2006). "Newly expressed SUR1-regulated NC(Ca-ATP) channel mediates cerebral edema after ischemic stroke". Nat Med 12 (4): 433–40. doi:10.1038/nm1390. PMC 2740734. PMID 16550187. 
  7. ^ Fournet JC, Junien C (2004). "Genetics of congenital hyperinsulinism". Endocr Pathol 15 (3): 233–40. doi:10.1385/EP:15:3:233. PMID 15640549. 
  8. ^ Reis AF, Velho G (2002). "Sulfonylurea receptor -1 (SUR1): genetic and metabolic evidences for a role in the susceptibility to type 2 diabetes mellitus". Diabetes Metab 28 (1): 14–9. PMID 11938023. 

External links[edit]