The function of Ensembl gene identifier ENSG00000197375 (SLC22A5, solute carrier family 22 member 5) is as follows. 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 B.subtilis which 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). {ECO:0000269|PubMed:10454528, ECO:0000269|PubMed:10525100, ECO:0000269|PubMed:10966938, ECO:0000269|PubMed:17509700, ECO:0000269|PubMed:18005709, ECO:0000269|PubMed:20722056, ECO:0000305|PubMed:35307651}. [Isoform 3]: Retained in the ER, unable to perform carnitine uptake. .