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SLC34 family of sodium phosphate co-transporters C

Unless otherwise stated all data on this page refer to the human proteins. Gene information is provided for human (Hs), mouse (Mm) and rat (Rn).


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The SLC34 family are sometimes referred to as Type II sodium-phosphate co-transporters, alongside Type I (SLC17 family) and Type III (SLC20 family) transporters. Topological modelling suggests eight TM domains with C- and N- termini in the cytoplasm, and a re-entrant loop at TM7/8. SLC34 family members are expressed on the apical surfaces of epithelia in the intestine and kidneys to regulate body phosphate levels, principally NaPi-IIa and NaPi-IIb, respectively. NaPi-IIa and NaPi-IIb are electrogenic, while NaPiIIc is electroneutral [1].


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NaPi-IIa (Sodium phosphate 1 / SLC34A1) C Show summary »

NaPi-IIb (Sodium phosphate 2 / SLC34A2) C Show summary »

Target Id 1136
Nomenclature Sodium phosphate 2
Systematic nomenclature SLC34A2
Common abbreviation NaPi-IIb
Previous and unofficial names NAPI-3B | Na(+)/Pi cotransporter 2B | Na(+)-dependent phosphate cotransporter 2B | naPi-2b | sodium/phosphate cotransporter 2B | sodium-dependent phosphate transport protein 2B | Npt2b | solute carrier family 34 (sodium phosphate), member 2 | solute carrier family 34 (type II sodium/phosphate contransporter), member 2 | solute carrier family 34 (type II sodium/phosphate cotransporter), member 2 | solute carrier family 34 (sodium phosphate)
Genes SLC34A2 (Hs), Slc34a2 (Mm), Slc34a2 (Rn)
Ensembl ID ENSG00000157765 (Hs), ENSMUSG00000029188 (Mm), ENSRNOG00000004626 (Rn)
UniProtKB AC O95436 (Hs), Q9DBP0 (Mm), Q9JJ09 (Rn)
Bioparadigms SLC Tables SLC34A2 (Hs)
compound 15 [PMID: 35034442] pIC50 7.2 [5]
lifastuzumab vedotin (Binding) [3]
Stoichiometry 3 Na+ : 1 HPO42- (in) [1]
Comment NaPi2b is highly expressed by ovarian and non-small cell lung cancer (NSCLC) carcinomas, and is being actively pursued as a drug target for these tumours. XMT-1536 (Mersana Therapeutics) has entered Phase 1 proof-of-concept trial NCT03319628. Lifastuzumab vedotin (Genentech) reached Phase 2 evaluation, but trial NCT01991210 was terminated as the test agent failed to increase progression-free survival compared to standard-of-care pegylated liposomal doxorubicin, in ovarian cancer patients [2]. XMT-1536 and lifastuzumab vedotin are NaPi2b-directed monoclonal antibody-drug conjugates (ADCs).

NaPi-IIc (Sodium phosphate 3 / SLC34A3) C Show summary »


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How to cite this family page

Database page citation:

SLC34 family of sodium phosphate co-transporters. Accessed on 21/04/2024. IUPHAR/BPS Guide to PHARMACOLOGY,

Concise Guide to PHARMACOLOGY citation:

Alexander SPH, Fabbro D, Kelly E, Mathie AA, Peters JA, Veale EL, Armstrong JF, Faccenda E, Harding SD, Davies JA et al. (2023) The Concise Guide to PHARMACOLOGY 2023/24: Transporters. Br J Pharmacol. 180 Suppl 2:S374-469.