SLC22A5
Function
Sodium-ion dependent, high affinity carnitine transporter. Involved in the active cellular uptake of carnitine. Transports one sodium ion with one molecule of carnitine (PubMed:10454528, PubMed:10525100, PubMed:10966938, PubMed:17509700, PubMed:20722056, PubMed:33124720). Also transports organic cations such as tetraethylammonium (TEA) without the involvement of sodium. Relative uptake activity ratio of carnitine to TEA is 11.3 (PubMed:10454528, PubMed:10525100, PubMed:10966938). In intestinal epithelia, transports the quorum-sensing pentapeptide CSF (competence and sporulation factor) from Bacillus Subtilis wich induces cytoprotective heat shock proteins contributing to intestinal homeostasis (PubMed:18005709). May also contribute to regulate the transport of organic compounds in testis across the blood-testis-barrier (Probable).
Isoform 3
Retained in the ER, unable to perform carnitine uptake.
Involvement in disease
Systemic primary carnitine deficiency
CDSP
Autosomal recessive disorder of fatty acid oxidation caused by defective carnitine transport. Present early in life with hypoketotic hypoglycemia and acute metabolic decompensation, or later in life with skeletal myopathy or cardiomyopathy.
None
The disease is caused by variants affecting the gene represented in this entry.
Expression in colon is increased in Crohn's disease and human ulcerative colitis (at protein level).
Post-translational modifications
Glycosylated. Glycosylation affects the expression levels.
Isoform 3
Not glycosylated.
Sequence Similarities
Belongs to the major facilitator (TC 2.A.1) superfamily. Organic cation transporter (TC 2.A.1.19) family.
Tissue Specificity
Strongly expressed in kidney, skeletal muscle, heart and placenta (PubMed:10454528). Primarily expressed by surface epithelial cells of the colon (at protein level) (PubMed:18005709). Expressed in CD68 macrophage and CD43 T-cells but not in CD20 B-cells (PubMed:10454528). In testis, localized to Sertoli cell basal membranes, peritubular myoid cells and Leydig cells (PubMed:35307651).
Cellular localization
- Cell membrane
- Multi-pass membrane protein
- Apical cell membrane
- Multi-pass membrane protein
- Basal cell membrane
- Multi-pass membrane protein
- In intestinal cells, apical expression is induced by TNF. Localized to the basal membrane of Sertoli cells (PubMed:35307651).
- Isoform 3
- Endoplasmic reticulum
Alternative names
OCTN2, SLC22A5, Organic cation/carnitine transporter 2, High-affinity sodium-dependent carnitine cotransporter, Solute carrier family 22 member 5