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1.A.2.1.12
G protein-activated inward rectifying K+ channel 1 (Kir3.1; IRK3; KCNJ3; GIRK1). Regulates the heartbeat in humans. Phosphatidylinositol bisphosphate (PIP2) activates by opening the intracelluar G-loop gate (Meng et al., 2012).  Along the ion permeation pathway, three relatively narrow regions (the selectivity filter, the inner helix bundle crossing, and the cytosolic G loop) may serve as gates to control ion permeation (Meng et al. 2016). Cholesterol up-regulates neuronal GIRK channel activity (Bukiya et al. 2017). Changes in the levels of cholesterol and PI(4,5)P2 may act in concert to provide fine-tuning of Kir3 channel function (Bukiya et al. 2017). Kir3.1 forms oligomers with Kir3.4 (TC# 1.A.2.1.3) and transporters Rb+ and spermine.  It has been suggested that the selectivity filter is responsible for inward rectification and agonist activation as well as permeation and block (Makary et al. 2006). Cytoplasmic domain structures of Kir2.1 and Kir3.1 show sites for modulating gating and rectification (Pegan et al. 2005).

Accession Number:P48549
Protein Name:G protein-activated inward rectifier potassium channel 1
Length:501
Molecular Weight:56603.00
Species:Homo sapiens (Human) [9606]
Number of TMSs:3
Location1 / Topology2 / Orientation3: Membrane1 / Multi-pass membrane protein2
Substrate potassium ions, K+

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FASTA formatted sequence
1:	MSALRRKFGD DYQVVTTSSS GSGLQPQGPG QDPQQQLVPK KKRQRFVDKN GRCNVQHGNL 
61:	GSETSRYLSD LFTTLVDLKW RWNLFIFILT YTVAWLFMAS MWWVIAYTRG DLNKAHVGNY 
121:	TPCVANVYNF PSAFLFFIET EATIGYGYRY ITDKCPEGII LFLFQSILGS IVDAFLIGCM 
181:	FIKMSQPKKR AETLMFSEHA VISMRDGKLT LMFRVGNLRN SHMVSAQIRC KLLKSRQTPE 
241:	GEFLPLDQLE LDVGFSTGAD QLFLVSPLTI CHVIDAKSPF YDLSQRSMQT EQFEIVVILE 
301:	GIVETTGMTC QARTSYTEDE VLWGHRFFPV ISLEEGFFKV DYSQFHATFE VPTPPYSVKE 
361:	QEEMLLMSSP LIAPAITNSK ERHNSVECLD GLDDITTKLP SKLQKITGRE DFPKKLLRMS 
421:	STTSEKAYSL GDLPMKLQRI SSVPGNSEEK LVSKTTKMLS DPMSQSVADL PPKLQKMAGG 
481:	AARMEGNLPA KLRKMNSDRF T