PortaCellTec biosciences GmbH


Molecular structure and tissue distribution
The organic cation and carnitine transporter OCTN1 (SLC22A4) is expressed in epithelial and muscle cells of various tissues. In human the highest expression was observed in kidney, skeletal muscle, bone marrow, and trachea and weaker expression was observed in many other organs. The human OCTN1 protein consists of 551 amino acids.

Interaction of hOCTN1 with endogenous compounds and drugs
Human OCTN1 transports the zwitterionic antioxidant ergothioneine with relatively high affinity. In addition, it transports the zwitterions L-carnitine and stachydrine and the organic cations TEA, quinidine, pyrilamine and verapamil. It has been shown that hOCTN1 is inhibited by many additional compounds. For example, OCTN1 mediated TEA uptake was inhibited by choline, L-carnitine, D-carnitine, cephaloridine, cimetidine, clonidine, levofloxacine, lidocaine, ofloxacine, procainamide, quinine, quinidine, tetrabutylammonium, tetrapentylammonium, nicotine, verapamil and the anticholinergic drug ipratropium as well as tiotropium.
OCTN1 is supposed to mediate the absorption of ergothioneine in small intestine and the reabsorption of ergothioneine in the kidney. The antioxidant ergothioneine is highly accumulated in plants as well as in mushrooms and reaches high concentrations in bone marrow and erythrocytes. It has been speculated that ergothioneine may protect erythrocytes and monocytes against oxidative damage. OCTN1 mediated uptake of ergothioneine in hematopoetic cells. The physiological role of OCTN1 in human renal proximal tubules is the reabsorption of zwitterions and the active secretion of endogenous as well as exogenous organic cations.



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)