The domains are encoded by separate genes, either by genes encoding one NBD and one TMD whose products dimerize to form the functional transporter, or by genes encoding two NBDs and two TMDs on a single polypeptide. In eukaryotic genomes, ABC genes are widely dispersed and highly conserved between species, indicating that most of these genes have existed since the beginning of eukaryotic evolution. ABC transporters can be classified into subfamilies according to sequence homology and domain topology. The existing eukaryotic genes have been grouped into major subfamilies, termed from ABCA to ABCI. Both subfamilies H and I are not present in humans. The subfamily ABCH was defined after the analysis of Terutroban the genome of the fruit fly Drosophila melanogaster and was found in other invertebrates and zebrafish to date. The subfamily ABCI is limited to plants. Most ABC proteins transport a wide range of compounds, either within the cell as part of a metabolic process into an intracellular compartment, mitochondria, and peroxisomes) or outside the cell for transport processes to other organs. In humans, the known functions of ABC transporters include cholesterol and lipid transport, multidrug resistance,APD668 antigen presentation, mitochondrial iron homeostasis and the ATP-dependent regulation of ion channels. Owing to the importance of ABC transporters for cell functions, they are still extensively investigated in many eukaryotes. In insects, one of the best studied ABC proteins is White, which is crucial for pigment transfer in insect eyes. As is known for D. melanogaster, ABC transporters facilitate translocation of attractants for germ cell migration or participate in the modulation of the molting hormones’ signaling in insect tissues. Furthermore, they seem to be frequently implicated in insecticide resistance, such as in the DTT tolerance of the Anopheles mosquitoes which transmit malaria agents or in the tolerance against pest control toxins from Bacillus thuringiensis which is reported of lepidopterans. Although ABC transporters were previously analyzed in several insect species at genome-wide level, profiles of the transcript levels of ABC transporters in non-model insects are not available to date.