Identification of multi-drug resistance associated proteins MRP1 (ABCC1) and MRP3 (ABCC3) from rainbow trout (Oncorhynchus mykiss).

The MRPs (multi-drug resistance associated proteins; ABCC subfamily) are members of the ATP binding cassette (ABC) superfamily of transport proteins and act as cellular efflux transporters of a wide variety of substrates, in particular glutathione, glucuronide and sulphate conjugates of diverse compounds. Together with P-gp (P-glycoprotein; MDR1; ABCB1) and BCRP (breast cancer resistance protein, ABCG2) the MRPs are highly important as cellular defense against toxicants and confer multixenobiotic resistance (MXR). In aquatic ecotoxicology MXR research has mostly focussed on P-glycoprotein while the other relevant ABC transporters are widely under-appreciated. We here present complete MRP1 (ABCC1) and partial MRP3 (ABCC3) cDNAs from rainbow trout (Oncorhynchus mykiss). We identified 4398bp of the MRP1 and 3786bp of the MRP3 open reading frames (ORF) by screening the NCBI EST database and by reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) using RNA from RTgill-W1 cells. Identities with human homologs are 56% for MRP1 and 64% for MRP3.