Organic Anion Transporters

Organic anion transporters (OATs) specialize in transporting organic anions (OAs), and most of the accumulated knowledge concerning OAT function has been found by studying prototypical substrates such as para-aminohippurate (PAH) and estrone-3-sulfate. OATs not only share high sequence homology, but they share many structural characteristics as well, including a sequence length of 500–600 amino acids, 12 transmembrane-spanning domains (TMDs), and cytosolic N- and C-termini. Identification of the specific proteins mediating OA secretion at the molecular level has allowed for the analysis of the pre- and postnatal ontogeny of the OATs, which may have clinical implications for the dosing of drugs to premature infants and full-term newborns, as well as pediatric patients. OATs are found in most barrier epithelia of the body, including the choroid plexus, blood– brain barrier, biliary tract, intestine, retinal–blood barrier, olfactory mucosa, and blood–testes barrier, among others.