Organic Cation Transporter

1. Organic Cation Transporter The organic cation transporter (OCT) is an important drug delivery protein with a broad tissue distribution in the body that mediates the metabolic processes of most drugs. At present, the gene sequence, transport mechanism, substrate structure specificity, regulatory mechanism, gene polymorphism andin vivodistribution characteristics of this transporter have been deeply studied. Based on this knowledge, pharmacologists have successfully delivered many drugs at the transporter molecule level and applied them to clinical practice. Since Grundemannet al. first cloned the first roct1 gene from a cDNA library of rat renal proximal tubular epithelial cells, human, rabbit, and mouse-derivedoct1were cloned one after another. This family is now named SLC22 (solute carrier family) and belongs to the solute transporter superfamily, including Oct1, Oct2 and Oct3. They have a similar structure and contain 12 transmembrane regions, an intracellular N-terminus, a large glycosylated extracellular hydrophilic ring between TM1 and TM2, and a TM6 and TM7, both of which have a high degree of homology. In the amino acid sequence, Oct1 and Oct2 are 70% similar (in which humans, rats, and mice are 68-69% similar, and human and rabbits are 71% similar). These Oct subtypes mediate the electrogenic transport of small molecule organic cations with different molecular structures that share a wide range of specific substrates. These organic cation substrates include type I organic cations, monovalent small molecule cations such as tetraethylamine (TEA), some important clinical drugs such procainamide, citalopram, cisplatin, cimetidine, some endogenous compounds such as dopamine, norepinephrine and some toxic substances RHPP+, HPP+, MPP+, etc. as metformin,