Q9JKZ2 · SC5A3_MOUSE

  • Protein
    Sodium/myo-inositol cotransporter
  • Gene
    Slc5a3
  • Status
    UniProtKB reviewed (Swiss-Prot)
  • Amino acids
  • Protein existence
    Evidence at protein level
  • Annotation score
    5/5

Function

function

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 (PubMed:12582158, PubMed:24595108).
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 (By similarity) (PubMed:24595108).
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 (PubMed:24595108).
Associates with KCNQ2-KCNQ3 channel altering ion selectivity, increasing Na+ and Cs+ permeation relative to K+ permeation (By similarity).
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 Ca2+ signaling upon osmotic stress (By similarity).
(Microbial infection) Functions as a retroviral receptor for M813 murine leukemia virus (MuLV) entry.

Catalytic activity

Features

Showing features for site.

TypeIDPosition(s)Description
Site24Implicated in sodium coupling
Site285Implicated in sodium coupling

GO annotations

AspectTerm
Cellular Componentapical plasma membrane
Cellular Componentbasolateral plasma membrane
Cellular Componentperinuclear region of cytoplasm
Cellular Componentplasma membrane
Cellular Componentvoltage-gated potassium channel complex
Molecular Functionglucose:sodium symporter activity
Molecular Functionmyo-inositol:sodium symporter activity
Molecular Functionpotassium channel regulator activity
Molecular Functiontransmembrane transporter binding
Biological Processinositol metabolic process
Biological Processmyo-inositol transport
Biological Processperipheral nervous system development
Biological Processpositive regulation of catalytic activity
Biological Processpositive regulation of protein localization to membrane
Biological Processpositive regulation of reactive oxygen species biosynthetic process
Biological Processregulation of respiratory gaseous exchange

Keywords

Enzyme and pathway databases

Names & Taxonomy

Protein names

  • Recommended name
    Sodium/myo-inositol cotransporter
  • Short names
    Na(+)/myo-inositol cotransporter
  • Alternative names
    • Sodium/myo-inositol transporter 1 (SMIT1)
    • Solute carrier family 5 member 3

Gene names

    • Name
      Slc5a3

Organism names

  • Taxonomic identifier
  • Taxonomic lineage
    Eukaryota > Metazoa > Chordata > Craniata > Vertebrata > Euteleostomi > Mammalia > Eutheria > Euarchontoglires > Glires > Rodentia > Myomorpha > Muroidea > Muridae > Murinae > Mus > Mus

Accessions

  • Primary accession
    Q9JKZ2
  • Secondary accessions
    • B2RU60

Proteomes

Organism-specific databases

Subcellular Location

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

Features

Showing features for topological domain, transmembrane.

TypeIDPosition(s)Description
Topological domain1-9Extracellular
Transmembrane10-29Helical
Topological domain30-38Cytoplasmic
Transmembrane39-57Helical
Topological domain58-86Extracellular
Transmembrane87-110Helical
Topological domain111-123Cytoplasmic
Transmembrane124-144Helical
Topological domain145-157Extracellular
Transmembrane158-183Helical
Topological domain184-186Cytoplasmic
Transmembrane187-205Helical
Topological domain206-303Extracellular
Transmembrane304-324Helical
Topological domain325-353Cytoplasmic
Transmembrane354-376Helical
Topological domain377-406Extracellular
Transmembrane407-430Helical
Topological domain431-443Cytoplasmic
Transmembrane444-462Helical
Topological domain463-510Extracellular
Transmembrane511-532Helical
Topological domain533-695Cytoplasmic
Transmembrane696-716Helical
Topological domain717-718Extracellular

Keywords

Phenotypes & Variants

Disruption phenotype

Mutant embryos show brain myo-inositol deficiency and central apnea and die soon after birth due to hypoventilation.

Variants

We now provide the "Disease & Variants" viewer in its own tab.

The viewer provides 32 variants from UniProt as well as other sources including ClinVar and dbSNP.

Go to variant viewer

PTM/Processing

Features

Showing features for chain, glycosylation, modified residue.

TypeIDPosition(s)Description
ChainPRO_00001053821-718Sodium/myo-inositol cotransporter
Glycosylation232N-linked (GlcNAc...) asparagine
Modified residue594Phosphoserine
Modified residue632Phosphoserine

Keywords

Proteomic databases

PTM databases

Expression

Tissue specificity

Highly expressed in kidney, placenta, and brain and at a lesser extent in thymus, lung, bladder, and testes (PubMed:12582158).
Expressed in the choroid plexus epithelium (at protein level) (PubMed:24595108).

Developmental stage

Expressed in placenta at 14.5 dpc.

Gene expression databases

Interaction

Subunit

Interacts with KCNQ2 (via the pore module) (By similarity).
Interacts with KCNQ1; this interaction is direct (PubMed:24595108).
Forms coregulatory complexes with ion channels KCNQ2-KCNQ3 and KCNQ1-KCNE2 (By similarity) (PubMed:24595108).

Protein-protein interaction databases

Miscellaneous

Structure

Family & Domains

Sequence similarities

Keywords

Phylogenomic databases

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Length
    718
  • Mass (Da)
    79,583
  • Last updated
    2011-07-27 v2
  • Checksum
    D0371D6ECF08503B
MRAVLEAADIAVVALYFILVMCIGFFAMWKSNRSTVSGYFLAGRSMTWVAIGASLFVSNIGSEHFIGLAGSGAASGFAVGAWEFNALLLLQLLGWVFIPIYIRSGVYTMPEYLSKRFGGHRIQVYFAALSLLLYIFTKLSVDLYSGALFIQESLGWNLYVSVILLIGMTALLTVTGGLVAVIYTDTLQALLMIIGALTLMVISMVKIGGFEEVKRRYMLASPDVASILLKYNLSNTNACMVHPKANALKMLRDPTDEDVPWPGFILGQTPASVWYWCADQVIVQRVLAAKNIAHAKGSTLMAGFLKLLPMFIIVVPGMISRIVFADEIACINPEHCMQVCGSRAGCSNIAYPRLVMTLVPVGLRGLMMAVMIAALMSDLDSIFNSASTIFTLDVYKLIRKSASSRELMIVGRIFVAFMVVISIAWVPIIVEMQGGQMYLYIQEVADYLTPPVAALFLLAIFWKRCNEQGAFYGGMAGFVLGAVRLILAFTYRAPECDQPDNRPGFIKDIHYMYVATALFWITGLITVIVSLLTPPPTKDQIRTTTFWSKKTLVTKESCSQKDEPYKMQEKSILQCSENSEVISHTIPNGKSEDSIKGLQPEDVNLLVTCREEGNPVASMGHSEAETPVDAYSNGQAALMGEREREKETENRSRYWKFIDWFCGFKSKSLSKRSLRDLMDEEAVCLQMLEETPQVKVILNIGLFAVCSLGIFMFVYFSL

Features

Showing features for sequence conflict.

TypeIDPosition(s)Description
Sequence conflict653in Ref. 1; AAF43668

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
AF220915
EMBL· GenBank· DDBJ
AAF43668.1
EMBL· GenBank· DDBJ
Genomic DNA
CH466602
EMBL· GenBank· DDBJ
EDL03793.1
EMBL· GenBank· DDBJ
Genomic DNA
BC140982
EMBL· GenBank· DDBJ
AAI40983.1
EMBL· GenBank· DDBJ
mRNA
BC140983
EMBL· GenBank· DDBJ
AAI40984.1
EMBL· GenBank· DDBJ
mRNA

Genome annotation databases

Similar Proteins

Disclaimer

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