TCDB is operated by the Saier Lab Bioinformatics Group
« See all members of the family


1.A.2.1.17
KCNJ11 or Kir6.2 or KATP of 390 aas; 96% identical to the rat homologue, TC# 1.A.2.1.7. Congenital hyperinsulinism (CHI) is characterized by persistent insulin secretion despite severe hypoglycemia. Mutations in the pancreatic ATP-sensitive K+ (K(ATP)) channel proteins sulfonylurea receptor 1 (SUR1) and Kir6.2, encoded by ABCC8 and KCNJ11, respectively, is the most common cause of the disease. Many mutations in SUR1 render the channel unable to traffic to the cell surface, thereby reducing channel function. Many studies have shown that for some SUR1 trafficking mutants, the defects could be corrected by treating cells with sulfonylureas or diazoxide (Yan et al. 2007). Inward rectifier potassium channels are characterized by a greater tendency to allow potassium to flow into the cell rather than out of it. Their voltage dependence is regulated by the concentration of extracellular potassium; as external potassium is raised, the voltage range of the channel opening shifts to more positive voltages. The inward rectification is mainly due to the blockage of outward current by internal magnesium (Tammaro and Ashcroft 2007). Kir6.2 is an ATP-sensitive potassium (KATP) channel coupling cell metabolism to electrical activity by regulating K+ fluxes across the plasma membrane. Channel closure is facilitated by ATP, which binds to the pore-forming subunit (Kir6.2). Conversely, channel opening is potentiated by phosphoinositol bisphosphate (PIP2), which binds to Kir6.2 and reduces channel inhibition by ATP.  The PIP2 binding site has been identified (Haider et al. 2007).  KATP channels are metabolic sensors that couple cell energetics to membrane excitability. In pancreatic beta-cells, channels formed by SUR1 and Kir6.2 regulate insulin secretion and are the targets of antidiabetic sulfonylureas. Martin et al. 2017 used cryo-EM to elucidate the structural basis of channel assembly and gating. The structure, determined in the presence of ATP and the sulfonylurea, glibenclamide, at ~6 Å resolution, revealed a closed Kir6.2 tetrameric core with four peripheral SUR1s, each anchored to a Kir6.2 by its N-terminal transmembrane domain (TMD0). Intricate interactions between TMD0, the loop following TMD0, and Kir6.2 near the proposed PIP2 binding site, and where ATP density is observed, suggest that SUR1 may contribute to ATP and PIP2 binding to enhance Kir6.2 sensitivity to both. The SUR1-ABC core is found in an unusual inward-facing conformation whereby the two nucleotide binding domains are misaligned along a two-fold symmetry axis, revealing a possible mechanism by which glibenclamide inhibits channel activity (Martin et al. 2017).

Accession Number:Q14654
Protein Name:ATP-sensitive inward rectifier potassium channel 11
Length:390
Molecular Weight:43541.00
Species:Homo sapiens (Human) [9606]
Number of TMSs:2
Location1 / Topology2 / Orientation3: Membrane1 / Multi-pass membrane protein2
Substrate potassium ions, K+

Cross database links:

External Searches:

  • Search: DB with
  • BLAST ExPASy (Swiss Institute of Bioinformatics (SIB) BLAST)
  • CDD Search (Conserved Domain Database)
  • Search COGs (Clusters of Orthologous Groups of proteins)
  • 2° Structure (Network Protein Sequence Analysis)

Analyze:

Predict TMSs (Predict number of transmembrane segments)
Window Size: Angle:  
Window Size: Angle:  
FASTA formatted sequence
1:	MLSRKGIIPE EYVLTRLAED PAEPRYRARQ RRARFVSKKG NCNVAHKNIR EQGRFLQDVF 
61:	TTLVDLKWPH TLLIFTMSFL CSWLLFAMAW WLIAFAHGDL APSEGTAEPC VTSIHSFSSA 
121:	FLFSIEVQVT IGFGGRMVTE ECPLAILILI VQNIVGLMIN AIMLGCIFMK TAQAHRRAET 
181:	LIFSKHAVIA LRHGRLCFML RVGDLRKSMI ISATIHMQVV RKTTSPEGEV VPLHQVDIPM 
241:	ENGVGGNSIF LVAPLIIYHV IDANSPLYDL APSDLHHHQD LEIIVILEGV VETTGITTQA 
301:	RTSYLADEIL WGQRFVPIVA EEDGRYSVDY SKFGNTIKVP TPLCTARQLD EDHSLLEALT 
361:	LASARGPLRK RSVPMAKAKP KFSISPDSLS