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2.A.36.1.19
Sodium/hydrogen exchanger 9 (Na+/H+ exchanger 9) (NHE-9; NHE9) (Solute carrier family 9 member 9, SLC9A9) of 645 aas and 12 TMSs. It may act in electroneutral exchange of protons for Na+ across membranes and is involved in the effusion of Golgi luminal H+ in exchange for cytosolic cations. It is also involved in organellar ion homeostasis by contributing to the maintenance of the unique acidic pH values of the Golgi and post-Golgi compartments in the cell (Nakamura et al. 2005). The cryogenic electron microscopy structure of NHE9 from Equus caballus at 3.2 A resolution has been determined (Winklemann et al. 2020). It is an endosomal isoform highly expressed in the brain and associated with autism spectrum (ASD) and attention deficit hyperactivity (ADHD) disorders in humans. The NHE9 architecture and ion-binding site are similar to distantly related bacterial Na+/H+ antiporters with 13 transmembrane segments. The conserved architecture of the NHE ion-binding site, their elevator-like structural transitions, the functional implications of autism disease mutations and the role of phosphoinositide lipids to promote homodimerization that, together, have important physiological ramifications have been revealed (Winklemann et al. 2020).  

Accession Number:Q8IVB4
Protein Name:Sodium/hydrogen exchanger 9
Length:645
Molecular Weight:72565.00
Species:Homo sapiens (Human) [9606]
Number of TMSs:12
Location1 / Topology2 / Orientation3: Late endosome membrane1 / Multi-pass membrane protein2
Substrate Na+, H+

Cross database links:

Entrez Gene ID: 285195   
Pfam: PF00999   
KEGG: hsa:285195   

Gene Ontology

GO:0016021 C:integral to membrane
GO:0031902 C:late endosome membrane
GO:0055037 C:recycling endosome
GO:0015385 F:sodium:hydrogen antiporter activity
GO:0006811 P:ion transport
GO:0006885 P:regulation of pH
GO:0055085 P:transmembrane transport

References (9)

[1] “Disruption of a novel member of a sodium/hydrogen exchanger family and DOCK3 is associated with an attention deficit hyperactivity disorder-like phenotype.”  De Silva M.G.et.al.   14569117
[2] “Four Na+/H+ exchanger isoforms are distributed to Golgi and post-Golgi Compartments and are involved in organelle pH regulation.”  Nakamura N.et.al.   15522866
[3] “The full-ORF clone resource of the German cDNA consortium.”  Bechtel S.et.al.   17974005
[4] “The DNA sequence, annotation and analysis of human chromosome 3.”  Muzny D.M.et.al.   16641997
[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] “Complete sequencing and characterization of 21,243 full-length human cDNAs.”  Ota T.et.al.   14702039
[7] “Neuroblastoma oligo-capping cDNA project: toward the understanding of the genesis and biology of neuroblastoma.”  Ohira M.et.al.   12880961
[8] “Identifying autism loci and genes by tracing recent shared ancestry.”  Morrow E.M.et.al.   18621663
[9] “Glycoproteomics analysis of human liver tissue by combination of multiple enzyme digestion and hydrazide chemistry.”  Chen R.et.al.   19159218

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FASTA formatted sequence
1:	MERQSRVMSE KDEYQFQHQG AVELLVFNFL LILTILTIWL FKNHRFRFLH ETGGAMVYGL 
61:	IMGLILRYAT APTDIESGTV YDCVKLTFSP STLLVNITDQ VYEYKYKREI SQHNINPHQG 
121:	NAILEKMTFD PEIFFNVLLP PIIFHAGYSL KKRHFFQNLG SILTYAFLGT AISCIVIGLI 
181:	MYGFVKAMIH AGQLKNGDFH FTDCLFFGSL MSATDPVTVL AIFHELHVDP DLYTLLFGES 
241:	VLNDAVAIVL TYSISIYSPK ENPNAFDAAA FFQSVGNFLG IFAGSFAMGS AYAIITALLT 
301:	KFTKLCEFPM LETGLFFLLS WSAFLSAEAA GLTGIVAVLF CGVTQAHYTY NNLSSDSKIR 
361:	TKQLFEFMNF LAENVIFCYM GLALFTFQNH IFNALFILGA FLAIFVARAC NIYPLSFLLN 
421:	LGRKQKIPWN FQHMMMFSGL RGAIAFALAI RNTESQPKQM MFTTTLLLVF FTVWVFGGGT 
481:	TPMLTWLQIR VGVDLDENLK EDPSSQHQEA NNLDKNMTKA ESARLFRMWY SFDHKYLKPI 
541:	LTHSGPPLTT TLPEWCGPIS RLLTSPQAYG EQLKEDDVEC IVNQDELAIN YQEQASSPCS 
601:	PPARLGLDQK ASPQTPGKEN IYEGDLGLGG YELKLEQTLG QSQLN