Figure 1.

Protein structure and conformation of MDR1.

MDR1 is composed of 12 transmembrane domains (TMs) and two cytoplasmic ATP binding domains located on the loop between the TMs 6 and 7 and the loop after the TM 12. The first extracellular loop is glycosylated. The location of the 3 most frequent MDR1 SNPs (C1236T, G2677T/A and C3435T) are reported on the molecule according to the location of their corresponding amino acid. Changes implied in amino acid are also indicated. Two (C1236T and C3435T) out of the three SNPs are silent mutations. They improve however transcription processes.