PortaCellTec biosciences GmbH

OCT1 (SLC22A1)

Molecular structure and Tissue distribution
OCT1 exhibits a broad tissue distribution. It is expressed in epithelial cells, some neurons, basophilic granulocytes and lymphocytes. In humans, it is most strongly expressed in the liver whereas in rodents, OCT1 is strongly expressed in liver, kidney and small intestine. In human and rat liver OCT1 has been localized to the sinusoidal membrane of hepatocytes and in mouse small intestine to the basolateral membrane of enterocytes. In rat kidney, OCT1 has been detected in the basolateral membrane of convoluted proximal tubles whereas in human kidney OCT1 has been localized to the luminal membrane of proximal and distal tubules. In the trachea and bronchi of human and rodents, OCT1 has is located in the luminal membrane of the epithelial cells.

Interaction of OCT1 with endogenous compounds and drugs.
Compounds that are transported by human hOCT1 include the model cations 1-methyl-4-phenyl-pyridinium (MPP) and tetraethylammonium (TEA), the endo­genous compounds choline, acetylcholine and agmatine. Drugs transported by human OCT1 are quinidine, quinine, acyclovir, ganciclovir, metformin and lamuvidine. For several drugs which inhibit OCTs but are not transported or have not been tested for transport, a higher affinity to hOCT1 was observed compared to hOCT2 or hOCT3. These include the glutamate receptor antagonist phencyclidine, the antagonists of histamine receptors diphenylhydramine and ranitidine, the antagonist of the muscarinic acetylcholine receptor atropine, and the antidepressant desipramine.

Example for biomedical impact: Diabetic patients with defect-mutations in OCT1 do not respond to treatment with metformin because metformin does not enter the hepatocytes and is excreted more rapidly in the kidney.

Figure 1 Concentration dependent OCT1 mediated MPP uptake Figure 2 Inhibition of OCT1 mediated MPP uptake by decynium22




New validated products:

  • MRP2
  • roct1


2nd German Pharm-Tox Summit
Heidelberg, Germany
March 06-09, 2017

19th Barrier- and

Bad Herrenalb, Germany
May 15-17, 2017

14th European ISSX Meeting
Köln, Germany

June 26- 29, 2017

2nd Symposium on Transporters in Drug Discovery
London, UK
May 15-16, 2017

Münster Transporttage 2017
Münster, Germany
October 21 – 22, 2017


Guidance for Industry (FDA and EMA)