Transportomics: screening for substrates of ABC transporters in body fluids using vesicular transport assays

Abstract

The ATP‐binding cassette (ABC) genes encode the largest family of transmembrane proteins. ABC transporters translocate a wide variety of substrates across membranes, but their physiological function is often incompletely understood. We describe a new method to study the substrate spectrum of ABC transporters: We incubate extracts of mouse urine with membrane vesicles prepared from Spodoptera frugiperda Sf9 insect cells overproducing an ABC transporter and determine the compounds transported into the vesicles by LC/MS‐based metabolomics. We illustrate the power of this simple “transportomics” approach using ABCC2, a protein present at sites of uptake and elimination. We identified many new substrates of ABCC2 in urine. These included glucuronides of plant‐derived xenobiotics, a class of compounds to which humans are exposed on a daily basis. Moreover, we show that the excretion of these compounds in vivo depends on ABCC2: compared to wild‐type mice, the urinary excretion of several glucuronides was increased up to 20‐fold in Abcc2 ‐/‐ mice. Transportomics has broad applicability, as it is not restricted to urine and can be applied to other ATP‐dependent transport proteins as well.—Krumpochova, P., Sapthu, S., Brouwers, J. F., de Haas, M., de Vos, R., Borst, P., van de Wetering, K. Transportomics: screening for substrates of ABC transporters in body fluids using vesicular transport assays. FASEB J. 26, 738–747 (2012). www.fasebj.org