SLC5A3

Electrogenic Na(+)-coupled sugar symporter that actively transports myo-inositol and its stereoisomer scyllo-inositol across the plasma membrane, with a Na(+) to sugar coupling ratio of 2:1 (By similarity). Maintains myo-inositol concentration gradient that defines cell volume and fluid balance during osmotic stress, in particular in the fetoplacental unit and central nervous system (By similarity). Forms coregulatory complexes with voltage-gated K(+) ion channels, allosterically altering ion selectivity, voltage dependence and gating kinetics of the channel. In turn, K(+) efflux through the channel forms a local electrical gradient that modulates electrogenic Na(+)-coupled myo-inositol influx through the transporter (PubMed:24595108, PubMed:28793216). Associates with KCNQ1-KCNE2 channel in the apical membrane of choroid plexus epithelium and regulates the myo-inositol gradient between blood and cerebrospinal fluid with an impact on neuron excitability (By similarity) (PubMed:24595108). Associates with KCNQ2-KCNQ3 channel altering ion selectivity, increasing Na(+) and Cs(+) permeation relative to K(+) permeation (PubMed:28793216). Provides myo-inositol precursor for biosynthesis of phosphoinositides such as PI(4,5)P2, thus indirectly affecting the activity of phosphoinositide-dependent ion channels and Ca(2+) signaling upon osmotic stress (PubMed:27217553).

Belongs to the sodium:solute symporter (SSF) (TC 2.A.21) family.

• Apical cell membrane
• Multi-pass membrane protein
• Basolateral cell membrane
• Multi-pass membrane protein
• Colocalizes with KCNQ1 at the apical membrane of choroid plexus epithelium.

Sodium/myo-inositol cotransporter, Na(+)/myo-inositol cotransporter, Sodium/myo-inositol transporter 1, Solute carrier family 5 member 3, SMIT1, SLC5A3

• entrezGene:6526
• omim:600444
• swissprot:P53794

Proteins

Immunology & Infectious Disease

79694Da