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1.A.9.3.1
Adult strychnine-sensitive glycine-inhibited chloride (anion selective) heteropentameric channel (GlyR; GLRA1) consisting of α1- and β-subunits (Cascio, 2004; Sivilotti, 2010). Ivermectin potentiates glycine-induced channel activation (Wang and Lynch, 2012). Molecular sites for the positive allosteric modulation of glycine receptors by endocannabinoids have been identified (Yévenes and Zeilhofer, 2011). Different subunits contribute asymmetrically to channel conductances via residues in the extracellular domain (Moroni et al., 2011; Xiong et al., 2012). Dominant and recessive mutations in GLRA1 are the major causes of hyperekplexia or startle disease (Gimenez et al., 2012).  Open channel 3-d structures are known (Mowrey et al. 2013).  Desensitization is regulated by interactions between the second and third transmembrane segments which affect the ion channel lumen near its intracellular end. The GABAAR and GlyR pore blocker, picrotoxin (TC# 8.C.1), prevents desensitization (Gielen et al. 2015).  The x-ray structure of the α1 GlyR transmembrane domain has been reported (Moraga-Cid et al. 2015), and residue S296 in hGlyR-alpha1 is involved in potentiation by Delta(9)-tetrahydrocannabinol (THC) (Wells et al. 2015).  The structure has also been elucidated by cryo EM (Du et al. 2015) and by x-ray crystalography (Huang et al. 2015). The latter presented a 3.0 A X-ray structure of the human glycine receptor-alpha3 homopentamer in complex with the high affinity, high-specificity antagonist, strychnine. The structure allowed exploration of the molecular recognition of antagonists. Comparisons with previous structures revealed a mechanism for antagonist-induced inactivation of Cys-loop receptors, involving an expansion of the orthosteric binding site in the extracellular domain that is coupled to closure of the ion pore in the transmembrane domain. The GlyR beta8-beta9 loop is an essential regulator of conformational rearrangements during ion channel opening and closing (Schaefer et al. 2017). Association of GlyR with the anchoring protein, gephyrin (Q9NQX3), is due to  a hydrophobic interaction formed by Phe 330 of gephyrin and Phe 398 and Ile 400 of the GlyR beta-loop (Kim et al. 2006). Alcohols and volatile anesthetics enhance the function of inhibitory glycine receptors (GlyRs) by binding to a single anaesthetic binding site (Roberts et al. 2006). Aromatic residues in the GlyR M1, M3 and M4 α-helices are essential for receptor function (Tang and Lummis 2018). The neurological disorder, startle disease, is caused by glycinergic dysfunction, mainly due to missense mutations in genes encoding GlyR subunits (GLRA1 and GLRB). Another neurological disease with a phenotype similar to startle disease is a special form of stiff-person syndrome (SPS), which is most probably due to the development of GlyR autoantibodies (Schaefer et al. 2018).

Accession Number:P23416
Protein Name:Glycine receptor subunit alpha-2 aka GLRA2
Length:452
Molecular Weight:52002.00
Species:Homo sapiens (Human) [9606]
Number of TMSs:4
Location1 / Topology2 / Orientation3: Cell junction1 / Multi-pass membrane protein2
Substrate Cl-

Cross database links:

Genevestigator: P23416
eggNOG: prNOG19428
HEGENOM: HBG506497
RefSeq: NP_001112357.1    NP_001112358.1    NP_001165413.1    NP_002054.1   
Entrez Gene ID: 2742   
Pfam: PF02931    PF02932   
Drugbank: Drugbank Link   
OMIM: 305990  gene
KEGG: hsa:2742   

Gene Ontology

GO:0030054 C:cell junction
GO:0034707 C:chloride channel complex
GO:0005887 C:integral to plasma membrane
GO:0045211 C:postsynaptic membrane
GO:0016934 F:extracellular-glycine-gated chloride channe...
GO:0016594 F:glycine binding
GO:0004872 F:receptor activity
GO:0006821 P:chloride transport
GO:0007218 P:neuropeptide signaling pathway

References (6)

[1] “Alpha subunit variants of the human glycine receptor: primary structures, functional expression and chromosomal localization of the corresponding genes.”  Grenningloh G.et.al.   2155780
[2] “Analysis of the genomic structure of the human glycine receptor alpha-2 subunit gene and exclusion of this gene as a candidate for Rett syndrome.”  Cummings C.J.et.al.   9674912
[3] “Differential agonist sensitivity of glycine receptor alpha2 subunit splice variants.”  Miller P.S.et.al.   15302677
[4] “Complete sequencing and characterization of 21,243 full-length human cDNAs.”  Ota T.et.al.   14702039
[5] “The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).”  The MGC Project Teamet.al.   15489334
[6] “Structure of the human alpha 2 subunit gene of the glycine receptor: use of vectorette and Alu-exon PCR.”  Monani U.R.et.al.   8973915

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FASTA formatted sequence
1:	MNRQLVNILT ALFAFFLETN HFRTAFCKDH DSRSGKQPSQ TLSPSDFLDK LMGRTSGYDA 
61:	RIRPNFKGPP VNVTCNIFIN SFGSVTETTM DYRVNIFLRQ QWNDSRLAYS EYPDDSLDLD 
121:	PSMLDSIWKP DLFFANEKGA NFHDVTTDNK LLRISKNGKV LYSIRLTLTL SCPMDLKNFP 
181:	MDVQTCTMQL ESFGYTMNDL IFEWLSDGPV QVAEGLTLPQ FILKEEKELG YCTKHYNTGK 
241:	FTCIEVKFHL ERQMGYYLIQ MYIPSLLIVI LSWVSFWINM DAAPARVALG ITTVLTMTTQ 
301:	SSGSRASLPK VSYVKAIDIW MAVCLLFVFA ALLEYAAVNF VSRQHKEFLR LRRRQKRQNK 
361:	EEDVTRESRF NFSGYGMGHC LQVKDGTAVK ATPANPLPQP PKDGDAIKKK FVDRAKRIDT 
421:	ISRAAFPLAF LIFNIFYWIT YKIIRHEDVH KK