Multiple drug resistance, and multidrug resistance (MDR ) describes the phenomenon that cells (eg tumor cells, tuberculosis pathogen) have or develop resistance to drugs. For this transporter may be responsible, which also inject these substances / drugs again from the cell.
Best known is the transporter MDR1 ( multidrug resistance protein 1): The glycoprotein with a mass of 170 kDa was known as P170 or P- glycoprotein and is the first of 49 previously characterized human ABC transporters. As original function of the MDR1 detoxification of the organism is accepted by foreign substances.
The MDR1 is, among other things occurring in Collies and related breeds genetic defect. The mode of inheritance is recessive. If a dog affected by MDR1, no multidrug resistance protein 1 is more formed and the dog can even die from certain medical drugs. This phenomenon has long been known under the term " Ivermectin - sensitive Collie ", but affected a far more active ingredients.
More responsible for multiple drug resistance active transport systems are the multidrug resistance -related proteins ( MRP).