Identification and characteristic of three members of the C1q/TNF-related proteins (CTRPs) superfamily in Eudontomyzon morii

C1q is the target recognition protein of the classical complement pathway and a major connecting link between innate and acquired immunity. C1q and the multifunctional tumor necrosis factor (TNF) ligand family is of similar crystal structures, are designated the C1q/TNF-related proteins (CTRPs) superfamily. They are involved in processes as diverse as host defense, inflammation, apoptosis, autoimmunity, cell differentiation, organogenesis, hibernation and insulinresistant obesity. In this study, three members of the CTRPs superfamily were isolated and characterized in Yalu River lampreys (Eudontomyzon morii), and are respectively named LaC1qC, LaCTRP1, LaCTRP9. The full-length cDNAs of C1qC-like (LaC1qAL), CTRP1-like (LaCTRP1), and CTRP9-like (LaCTRP9) consist of 723, 762 and 825 bp of nucleotide sequence encoding polypeptides of 241, 254 and 275 amino acids, respectively. All-three proteins share three common domains: a signal peptide at the N terminus, a collagenous domain (characteristic Gly-X-Y repeats), and a C-terminal globular domain. In addition, the higher expression level of the three proteins in heart by RT-PCR and real-time PCR tissue profiling implied that they might involve in immune response or injury repair of the heart in lamprey.