In D. melanogaster, the ABCE homolog Pixie plays a catalytic role in the assembly of protein complexes required for translation initiation. All genomes of multicellular eukaryotes analyzed to date possess one ABCE gene. In the transcript catalogue of C. populi,Saikosaponin D one complete ABCE protein has been predicted. The NBDs of CpABC45 are highly conserved with the respective NBDs of the human ABCE1 and T. castaneum TcABCE-3A. Among the subfamily ABCF involved in translation initiation and elongation in humans, we found in C. populi three putative members each with two NBDs that are highly similar to the transporters of human and T. castaneum suggesting functional proteins used in similar physiological processes in the cell. The ABCG subfamily in humans is comprised of five half transporters. While the homodimer ABCG2 is a multidrug transporter with a wide substrate specificity,Tetrahydropalmatine the homodimers ABCG1 and ABCG4 and the heterodimer ABCG5:ABCG8 translocate cholesterol and other sterole derivatives. In insects, ABCG transporters are essential for the translocation of ommochromes for the pigmentation of eyes and body coloration. In D. melanogaster, for example, the half transporter White forms heterodimers with Scarlet or Brown, each of which is responsible for the transport of another type of ommochrome precursor to pigment granules. In silkworms, White-orthologs are responsible for the translocation of uric acid for accumulation in urate granules in epidermal cells, resulting in opaque white coloration of the larval skin. In D. melanogaster, E23 encodes a transporter capable of modulating the ecdysone response with consequences for the circadian transcription of clock genes. To link the above suggested functions for the C. populi ABC proteins to those which are differentially expressed in the larval tissues of C. populi, we carried out a comprehensive transcriptome sequencing of different tissues dissected from the poplar leaf beetle. All raw sequence data are listed in Table S3 and S4. The resulting expression patterns of all identified ABC transporters in intestinal tissue, Malpighian tubules, fat body and defensive glands is depicted in Figure 6.