SLC5A3: Sodium/Myo-Inositol Cotransporter
A key regulator of cellular osmolarity and inositol homeostasis
Gene Information Card
| Symbol | SLC5A3 |
|---|---|
| Full Name | Solute carrier family 5 member 3 |
| Gene Type | protein-coding |
| Chromosomal Location | 21q22.12 |
| NCBI Gene ID | 6526 ncbi.nlm.nih.gov/gene/6526 |
| Ensembl ID | ENSG00000198719 |
| UniProt ID | P53794 |
| OMIM ID | 600444 |
| HGNC ID | 11038 |
| Aliases | SMIT1, SMIT, SMIT2 |
Description
SLC5A3 encodes the sodium/myo-inositol cotransporter (SMIT1), a plasma membrane protein that mediates the electrogenic uptake of myo-inositol coupled with sodium ions. This transporter is critical for cellular osmotic regulation by accumulating inositol as a compatible osmolyte. It is expressed in kidney, brain, and other tissues, and its expression is induced by hypertonic stress.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Down syndrome | Overexpression of SLC5A3 on chromosome 21 may contribute to altered inositol metabolism and cognitive deficits. | PubMed, OMIM |
| Diabetic nephropathy | Altered inositol transport in renal cells under hyperglycemic conditions may exacerbate osmotic stress. | PubMed, NCBI |
| Myo-inositol deficiency | Loss-of-function variants impair cellular inositol uptake, potentially affecting neural and renal function. | ClinVar, OMIM |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Kidney | 12.5 | High |
| Brain | 8.3 | Medium |
| Liver | 2.1 | Low |
| Heart | 1.8 | Low |
| Testis | 0.9 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 15.2 | High expression |
| SH-SY5Y | 9.8 | Neuronal model |
| HepG2 | 3.4 | Low expression |
| A549 | 1.1 | Not detected |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.100C>T (p.Arg34Trp) | Missense | <0.01% | Likely benign; no functional data |
| c.452G>A (p.Arg151Gln) | Missense | <0.01% | Uncertain significance |
| c.1234delC | Frameshift | <0.01% | Predicted loss of function |
Mutation functional classification
Loss of Function (LOF)
Frameshift and nonsense variants predicted to truncate the protein, impairing inositol transport.
Gain of Function (GOF)
Not reported.
Dominant Negative (DN)
Not reported.
View complete mutation data：
Gene Ontology (GO)
| • myo-inositol:sodium symporter activity (GO:0005369) | • L-amino acid transmembrane transporter activity (GO:0015179) |
| • integral component of membrane (GO:0016021) | • sodium ion transport (GO:0006814) |
| • myo-inositol transport (GO:0015758) | • response to osmotic stress (GO:0006970) |
Pathways
• Inositol phosphate metabolism (Reactome: R-HSA-1483249)
• SLC-mediated transmembrane transport (Reactome: R-HSA-425407)
• Transport of inorganic cations/anions and amino acids/oligopeptides (Reactome: R-HSA-425393)
Protein Summary
The SLC5A3 protein (SMIT1) is a 718-amino acid transmembrane transporter with 14 predicted membrane-spanning domains. It functions as a sodium-coupled symporter for myo-inositol, a key osmolyte and precursor for phosphoinositide signaling. The protein is localized to the plasma membrane and is upregulated under hypertonic conditions via a tonicity-responsive enhancer element.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SLC5A3 Knockout HEK293 Cell Line | EDJ-KQ5769 | Human | 6526 | Details Get a Quote |
| SLC5A3 Knockout A-549 Cell Line | EDJ-KQ29184 | Human | 6526 | Details Get a Quote |
| SLC5A3 Knockout HCT 116 Cell Line | EDJ-KQ29185 | Human | 6526 | Details Get a Quote |
| SLC5A3 Knockout HeLa Cell Line | EDJ-KQ29186 | Human | 6526 | Details Get a Quote |
Displaying Records 1 To 4 Of 4 Records
