Channel catfish (Ictalurus punctatus Rafinesque, 1818) CD156a (ADAM metallopeptidase domain 8): cDNA clone, characterization and expression in tissues

CD156a, also known as a disintegrin and metalloprotease domain 8 (ADAM-8), is a type 1 transmembrane glycoprotein of the ADAM family. This protein plays important roles in immune and other physiological functions. In this communication, the channel catfish CD156a cDNA was characterized and its expression in various tissues was determined. The full-length of channel catfish CD156a cDNA had 3035 nucleotides, including an open reading frame which appears to encode an 850 amino acid peptide with a calculated molecular mass of 94.6 kDa. The peptide had three potential N-glycosylation sites. By comparison with other species, the degree of homology of the CD156a amino acid sequences ranged from 31.6% (vs. chicken CD156a) to 59.5% (vs. zebrafish CD156a). The channel catfish CD156a peptide could be structurally divided into nine domains. Several canonical features for CD156a functions were conserved in channel catfish. The CD156a transcript was detected by two-step RT-PCR in anterior kidney and gill, suggesting that CD156a may be involved in the innate immune response in channel catfish. Reagents for further elucidating the immune functions of channel catfish CD156a are under development.