The function of ENSG00000197208 (SLC22A4, solute carrier family 22 member 4) is as follows. Transporter that mediates the transport of endogenous and microbial zwitterions and organic cations (PubMed:10215651, PubMed:15107849, PubMed:15795384, PubMed:16729965, PubMed:20601551, PubMed:22206629, PubMed:22569296, PubMed:29530864). Functions as a Na(+)-dependent and pH-dependent high affinity microbial symporter of potent food-derived antioxidant ergothioeine (PubMed:15795384, PubMed:29530864, PubMed:33124720). Transports one sodium ion with one ergothioeine molecule (By similarity). Involved in the absorption of ergothioneine from the luminal/apical side of the small intestine and renal tubular cells, and into non-parenchymal liver cells, thereby contributing to maintain steady-state ergothioneine level in the body (PubMed:20601551). Also mediates the bidirectional transport of acetycholine, although the exact transport mechanism has not been fully identified yet (PubMed:22206629). Most likely exports anti-inflammatory acetylcholine in non-neuronal tissues, thereby contributing to the non- neuronal cholinergic system (PubMed:22206629, PubMed:22569296). Displays a general physiological role linked to better survival by controlling inflammation and oxidative stress, which may be related to ergothioneine and acetycholine transports (PubMed:15795384, PubMed:22206629). May also function as a low-affinity Na(+)-dependent transporter of L-carnitine through the mitochondrial membrane, thereby maintaining intracellular carnitine homeostasis (PubMed:10215651, PubMed:15107849, PubMed:16729965). May contribute to regulate the transport of cationic compounds in testis across the blood-testis- barrier (PubMed:35307651). {ECO:0000250|UniProtKB:Q9R141, ECO:0000269|PubMed:10215651, ECO:0000269|PubMed:15107849, ECO:0000269|PubMed:15795384, ECO:0000269|PubMed:16729965, ECO:0000269|PubMed:20601551, ECO:0000269|PubMed:22206629, ECO:0000269|PubMed:22569296, ECO:0000269|PubMed:29530864, ECO:0000269|PubMed:35307651}.