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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).
Three different mammalian myo-inositol cotransporters are currently known; two are the Na+-coupled SMIT1 and SMIT2 tabulated below and the third is proton-coupled HMIT (SLC2A13). SMIT1 and SMIT2 have a widespread and overlapping tissue location but in polarized cells, such as the Madin-Darby canine kidney cell line, they segregate to the basolateral and apical membranes, respectively . In the nephron, SMIT1 mediates myo-inositol uptake as a ‘compatible osmolyte’ when inner medullary tubules are exposed to increases in extracellular osmolality, whilst SMIT2 mediates the reabsorption of myo-inositol from the filtrate. In some species (e.g. rat, but not rabbit) apically located SMIT2 is responsible for the uptake of myo-inositol from the intestinal lumen .
1. Aouameur R, Da Cal S, Bissonnette P, Coady MJ, Lapointe JY. (2007) SMIT2 mediates all myo-inositol uptake in apical membranes of rat small intestine. Am. J. Physiol. Gastrointest. Liver Physiol., 293 (6): G1300-7. [PMID:17932225]
2. Bissonnette P, Coady MJ, Lapointe JY. (2004) Expression of the sodium-myo-inositol cotransporter SMIT2 at the apical membrane of Madin-Darby canine kidney cells. J. Physiol. (Lond.), 558 (Pt 3): 759-68. [PMID:15181167]
3. Bourgeois F, Coady MJ, Lapointe JY. (2005) Determination of transport stoichiometry for two cation-coupled myo-inositol cotransporters: SMIT2 and HMIT. J. Physiol. (Lond.), 563 (Pt 2): 333-43. [PMID:15613375]
4. Coady MJ, Wallendorff B, Gagnon DG, Lapointe JY. (2002) Identification of a novel Na+/myo-inositol cotransporter. J. Biol. Chem., 277 (38): 35219-24. [PMID:12133831]
5. Hager K, Hazama A, Kwon HM, Loo DD, Handler JS, Wright EM. (1995) Kinetics and specificity of the renal Na+/myo-inositol cotransporter expressed in Xenopus oocytes. J. Membr. Biol., 143 (2): 103-13. [PMID:7537337]
6. Lin X, Ma L, Fitzgerald RL, Ostlund RE. (2009) Human sodium/inositol cotransporter 2 (SMIT2) transports inositols but not glucose in L6 cells. Arch. Biochem. Biophys., 481 (2): 197-201. [PMID:19032932]
Database page citation:
Sodium myo-inositol cotransporter transporters. Accessed on 30/04/2017. IUPHAR/BPS Guide to PHARMACOLOGY, http://www.guidetopharmacology.org/GRAC/FamilyDisplayForward?familyId=175.
Concise Guide to PHARMACOLOGY citation:
Alexander SPH, Kelly E, Marrion N, Peters JA, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Southan C, Davies JA and CGTP Collaborators (2015) The Concise Guide to PHARMACOLOGY 2015/16: Transporters. Br J Pharmacol. 172: 6110-6202.