They are crucial for the disposal of many organic cations that come from drugs or other environmental sources.
For example, the disposing of the blood sugar medication Metformin is dependent on organic cation transport proteins[1].
The general structure of an OCT or OCTN consists of 11-12 alpha-helical transmembrane protein domains.
There is also an intracellular loop between the transmembrane domains 6 and 7 that contains phosphorylation sites that are believed to contribute to regulation of activity of the organic cation transport protein.
The various types of organic cation transport proteins are often referred to in its respective abbreviated form or by the gene that codes it.