Tumor necrosis factor receptor-associated factor 6 (TRAF6) and transforming growth factor-β-activatedkinase 1 (TAK1) are important adaptor molecules in Toll-like receptor (TLR) signaling pathways. To better understandthe biological role of these two genes in immune response, we cloned ) using homologous cloning methods and rapid amplification of cDNAends. We also detected the expression patterns of these two genes in different tissues at different developmental stages.The full-length cDNA sequence of was 1956 bp, including a 1731 bp open reading frame (ORF) that encoded aputative 576 amino acid protein. TRAF6 contained one RING domain, two zinc fingers, one coiled-coil region, and oneMATH domain; this structure is highly similar to that of TRAF6 in other species. The conserved motifs of TRAF6likely indicate that its functions are similar to those of other mammal TRAF6s. The full-length cDNA sequencewas 2519 bp, including a 1731 bp ORF that encoded a putative 576 amino acid protein. TAK1 contains a conservedserine/threonine protein kinase catalytic domain and a coiled-coil region. The highly conserved domains indicate that allTAK1s have a similar function. Phylogenetic trees showed that both TRAF6 and TAK1 in In addition, the expression patterns of these two genes were examinedin different tissues and developmental stages. was expressed in all tested tissues, and the highest expressionwas in the gills followed by the intestines. in the gills and kidneys were consistent with the essential role of the two genes in the TLR/Toll-likereceptor signaling pathway, which is pivotal in both innate and adaptive immune responses. wereexpressed throughout developmental stages, including unfertilized eggs, indicating maternal inheritance of . The expression of maternal mRNA throughout development demonstrates the potential role of . These results indicate that TRAF6 and TAK1may play crucial roles in immune responses and might be involved in half-smooth tongue sole development. This studyprovides a theoretical basis for understanding the roles of these two genes in