Unusual expression of an Arabidopsis ATP-binding cassette transporter ABCC11

Abstract

Plant genomes contain more than 120 genes encoding ATP-binding cassette (ABC) proteins, which can be classified into 8 groups. Among them, ABCC/MRP (Multidrug resistance-associated protein) family members are proposed to function in general as MgATP-energized pumps involved in detoxification mechanisms, mainly by transporting glutathione-xenobiotic (GS-X) conjugates and other bulky amphipathic anions across membranes. Recent reports demonstrated that 15 ABCC subfamily members in Arabidopsis thaliana are widely expressed in the plant body and suggested that these proteins play a general function for the survival of plant cells. In this study, it was found that a member of this family, AtABCC11, which was thought to encode a full-sized ABCC-type transporter, gives an unusual transcript of a much smaller size than the full-size mRNA covering the entire open reading frame, and therefore may not be functional as a full-sized ABC transporter in plants. This study also assessed the promoter activity of AtABCC11 compared with its closest paralogue, AtABCC12.