Only one of the flounder C7 factor I domain was complete, with several amino acids deleted from the C-terminus of the second. Two thrombospondin domains are present in Japanese flounder C9, a feature which has more resemblance to human C8 alpha and C8 beta than with human C9. Cysteine residues were highly conserved all components regardless of flounder or human origin. Collectively these features emphasize the great similarity among the terminal complement family.
Complement system is presumed to have ancient genetic orientation.
To analyze these genes in Japanese flounder, we constructed the genomic BAC library and isolated BAC clones of C7 and C8 beta.