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2.A.58.1.5
Sodium-dependent phosphate transport protein 2A (Sodium-phosphate transport protein 2A; Na+-dependent phosphate cotransporter 2A; NaPiIIa; NaPi-3; NaPi-2a) (Solute carrier family 34 member 1; SLC34A1) of 639 aas and 12 TMSs. Structure-function relationships of the first and fourth predicted extracellular linkers of the type IIa Na+/Pi cotransporter have been stidied (Ehnes et al. 2004). It co-transports 3 Na+ with 1 divalent phosphate anion.  There are 3 Na+ binding sites, N1 (binds Na+ or Li+), N2 and N3, (both of which are Na+-specific); residues comprising N1 have been identified (Fenollar-Ferrer et al. 2015). Glucocorticoid-induced acute diuresis in rats is due to reduced renal expression of sodium-dependent cotransporter genes (Zhao et al. 2024).  Glucocorticoids, including dexamethasone (Dex) and prednisolone (PSL), acutely induced diuresis. Dex significantly increased the urinary excretion of sodium, potassium, chloride, glucose, and inorganic phosphorus by increasing expression of the Na+-dependent transporter genes (Zhao et al. 2024).  Renal Pi transporters are regulated, may provide novel drug targets for prevention or treatment of hyperphosphatemia, and contribute to the genetic risk to develop kidney stones and CKD (Wagner et al. 2025).

Accession Number:Q06495
Protein Name:Sodium-dependent phosphate transport protein 2A
Length:639
Molecular Weight:68937.00
Species:Homo sapiens (Human) [9606]
Number of TMSs:12
Location1 / Topology2 / Orientation3: Membrane1 / Multi-pass membrane protein2
Substrate lithium(1+), sodium(1+), phosphate(3-)

Cross database links:

Entrez Gene ID: 6569   
Pfam: PF02690   
KEGG: hsa:6569   

Gene Ontology

GO:0016323 C:basolateral plasma membrane
GO:0031526 C:brush border membrane
GO:0005887 C:integral to plasma membrane
GO:0015321 F:sodium-dependent phosphate transmembrane transporter activity
GO:0015293 F:symporter activity
GO:0046849 P:bone remodeling
GO:0055062 P:phosphate ion homeostasis
GO:0046686 P:response to cadmium ion
GO:0010288 P:response to lead ion
GO:0032026 P:response to magnesium ion
GO:0046689 P:response to mercury ion
GO:0006814 P:sodium ion transport

References (6)

[1] “Expression cloning of human and rat renal cortex Na/Pi cotransport.”  Magagnin S.et.al.   8327470
[2] “Complete sequencing and characterization of 21,243 full-length human cDNAs.”  Ota T.et.al.   14702039
[3] “The DNA sequence and comparative analysis of human chromosome 5.”  Schmutz J.et.al.   15372022
[4] “A new human NHERF1 mutation decreases renal phosphate transporter NPT2a expression by a PTH-independent mechanism.”  Courbebaisse M.et.al.   22506049
[5] “Nephrolithiasis and osteoporosis associated with hypophosphatemia caused by mutations in the type 2a sodium-phosphate cotransporter.”  Prie D.et.al.   12324554
[6] “A loss-of-function mutation in NaPi-IIa and renal Fanconi's syndrome.”  Magen D.et.al.   20335586

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Predict TMSs (Predict number of transmembrane segments)
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FASTA formatted sequence 
1:	MLSYGERLGS PAVSPLPVRG GHVMRGTAFA YVPSPQVLHR IPGTSAYAFP SLGPVALAEH 
61:	TCPCGEVLER HEPLPAKLAL EEEQKPESRL VPKLRQAGAM LLKVPLMLTF LYLFVCSLDM 
121:	LSSAFQLAGG KVAGDIFKDN AILSNPVAGL VVGILVTVLV QSSSTSTSII VSMVSSGLLE 
181:	VSSAIPIIMG SNIGTSVTNT IVALMQAGDR TDFRRAFAGA TVHDCFNWLS VLVLLPLEAA 
241:	TGYLHHITRL VVASFNIHGG RDAPDLLKII TEPFTKLIIQ LDESVITSIA TGDESLRNHS 
301:	LIQIWCHPDS LQAPTSMSRA EANSSQTLGN ATMEKCNHIF VDTGLPDLAV GLILLAGSLV 
361:	LLCTCLILLV KMLNSLLKGQ VAKVIQKVIN TDFPAPFTWV TGYFAMVVGA SMTFVVQSSS 
421:	VFTSAITPLI GLGVISIERA YPLTLGSNIG TTTTAILAAL ASPREKLSSA FQIALCHFFF 
481:	NISGILLWYP VPCTRLPIRM AKALGKRTAK YRWFAVLYLL VCFLLLPSLV FGISMAGWQV 
541:	MVGVGTPFGA LLAFVVLINV LQSRSPGHLP KWLQTWDFLP RWMHSLKPLD HLITRATLCC 
601:	ARPEPRSPPL PPRVFLEELP PATPSPRLAL PAHHNATRL