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2.A.53.2.15
Solute carrier family 26 member 9 (Anion transporter/exchanger protein 9).  May play a role in chronic inflammatory airway diseases (Sala-Rabanal et al. 2015). The Cl--transporting proteins CFTR (TC# 3.A.1.202.1), SLC26A9, and anoctamin (ANO1; ANO6) (see TC family 1.A.17)  all participate in the pathogenic process and clinical outcomes of airway and renal diseases (Kunzelmann et al. 2023). The molecular principles underlying diverse functions of the SLC26 family of proteins (Takahashi and Homma 2023).  (i) The basic residue at the anion binding site is essential for both anion antiport of SLC26A4 and motor functions of SLC26A5, and its conversion to a nonpolar residue is crucial but not sufficient for the fast uncoupled anion transport in SLC26A9; (ii) the conserved polar residues in the N- and C-terminal cytosolic domains are likely involved in dynamic hydrogen-bonding networks and are essential for anion antiport of SLC26A4 but not for motor (SLC26A5) and uncoupled anion transport (SLC26A9) functions; (iii) the hydrophobic interaction between each protomer's last transmembrane helices, TM14, is not of functional significance in SLC26A9 but crucial for the functions of SLC26A4 and SLC26A5, likely contributing to optimally orient the axis of the relative movements of the core domain with respect to the gate domains within the cell memSala-Rabanal et al. 2015). The Cl--transporting proteins CFTR (TC# 3.A.1.202.1), SLC26A9, and anoctamin (ANO1; ANO6) (see TC family 1.A.17)  all participate in the pathogenic process and clinical outcomes of airway and renal diseases (Kunzelmann et al. 2023). The molecular principles underlying diverse functions of the SLC26 family of proteins (Takahashi and Homma 2023).  (i) The basic residue at the anion binding site is essential for both anion antiport of SLC26A4 and motor functions of SLC26A5, and its conversion to a nonpolar residue is crucial but not sufficient for the fast uncoupled anion transport in SLC26A9; (ii) the conserved polar residues in the N- and C-terminal cytosolic domains are likely involved in dynamic hydrogen-bonding networks and are essential for anion antiport of SLC26A4 but not for motor (SLC26A5) and uncoupled anion transport (SLC26A9) functions; (iii) the hydrophobic interaction between each protomer's last transmembrane helices, TM14, is not of functional significance in SLC26A9 but crucial for the functions of SLC26A4 and SLC26A5, likely contributing to optimally orient the axis of the relative movements of the core domain with respect to the gate domains within the cell membrane (Takahashi and Homma 2023).

Accession Number:Q7LBE3
Protein Name:Solute carrier family 26 member 9
Length:791
Molecular Weight:86988.00
Species:Homo sapiens (Human) [9606]
Number of TMSs:11
Location1 / Topology2 / Orientation3: Membrane1 / Multi-pass membrane protein2
Substrate anion

Cross database links:

Entrez Gene ID: 115019   
Pfam: PF01740    PF00916   
KEGG: hsa:115019   

Gene Ontology

GO:0016324 C:apical plasma membrane
GO:0016021 C:integral to membrane
GO:0005886 C:plasma membrane
GO:0015301 F:anion:anion antiporter activity
GO:0015106 F:bicarbonate transmembrane transporter activity
GO:0008271 F:secondary active sulfate transmembrane transporter activity
GO:0006821 P:chloride transport
GO:0006811 P:ion transport
GO:0006885 P:regulation of pH
GO:0055085 P:transmembrane transport

References (4)

[1] “Functional characterization of three novel tissue-specific anion exchangers SLC26A7, -A8, and -A9.”  Lohi H.et.al.   11834742
[2] “The DNA sequence and biological annotation of human chromosome 1.”  Gregory S.G.et.al.   16710414
[3] “The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).”  The MGC Project Teamet.al.   15489334
[4] “SLC26A9 is expressed in gastric surface epithelial cells, mediates Cl-/HCO3- exchange, and is inhibited by NH4+.”  Xu J.et.al.   15800055
Structure:
7CH1     

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Predict TMSs (Predict number of transmembrane segments)
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FASTA formatted sequence
1:	MSQPRPRYVV DRAAYSLTLF DDEFEKKDRT YPVGEKLRNA FRCSSAKIKA VVFGLLPVLS 
61:	WLPKYKIKDY IIPDLLGGLS GGSIQVPQGM AFALLANLPA VNGLYSSFFP LLTYFFLGGV 
121:	HQMVPGTFAV ISILVGNICL QLAPESKFQV FNNATNESYV DTAAMEAERL HVSATLACLT 
181:	AIIQMGLGFM QFGFVAIYLS ESFIRGFMTA AGLQILISVL KYIFGLTIPS YTGPGSIVFT 
241:	FIDICKNLPH TNIASLIFAL ISGAFLVLVK ELNARYMHKI RFPIPTEMIV VVVATAISGG 
301:	CKMPKKYHMQ IVGEIQRGFP TPVSPVVSQW KDMIGTAFSL AIVSYVINLA MGRTLANKHG 
361:	YDVDSNQEMI ALGCSNFFGS FFKIHVICCA LSVTLAVDGA GGKSQVASLC VSLVVMITML 
421:	VLGIYLYPLP KSVLGALIAV NLKNSLKQLT DPYYLWRKSK LDCCIWVVSF LSSFFLSLPY 
481:	GVAVGVAFSV LVVVFQTQFR NGYALAQVMD TDIYVNPKTY NRAQDIQGIK IITYCSPLYF 
541:	ANSEIFRQKV IAKTGMDPQK VLLAKQKYLK KQEKRRMRPT QQRRSLFMKT KTVSLQELQQ 
601:	DFENAPPTDP NNNQTPANGT SVSYITFSPD SSSPAQSEPP ASAEAPGEPS DMLASVPPFV 
661:	TFHTLILDMS GVSFVDLMGI KALAKLSSTY GKIGVKVFLV NIHAQVYNDI SHGGVFEDGS 
721:	LECKHVFPSI HDAVLFAQAN ARDVTPGHNF QGAPGDAELS LYDSEEDIRS YWDLEQEMFG 
781:	SMFHAETLTA L