Amino acid sequences of N-terminal procalcitonin of some vertebrates

In the present study, the complete amino acid sequence of N-terminal procalcitonins (N-proCTs) of stingray tan elasmobranch) and spotlined sardine (a teleost), as well as the partial amino acid sequence of N-proCTs of goldfish (a teleost; three types of N-proCTs) and bullfrog tan amphibian) have been determined. These N-proCTs have some common features to 9 N-proCTs sequenced to date. These features were summarized as follows: 1) The first amino acid residue is Ala or Val. 2) There is no Cys residue in the sequence of N-proCTs. 3) Seven residues (Pro(3), Leu(19), Leu(28), Val(32), Gln(37), Gln(45) and Ser(56)) are conserved in the sequence of N-terminal procalcitonin (N-proCT), at least judging from the present data. 4) Insertion/deletion points are present in the sequence of N-proCTs at the 2nd position, from the 10th to 14th and from 46th to 52nd. We examined whether the N-proCTs can be categorized into several groups by similarity of amino acid residues conserved in the molecules. Asa result, the N-proCTs were roughly categorized into 2 groups: a mammalian group, including 2 subgroups and a non-mammalian group, including 3 subgroups. This classification of N-proCTs coincides with that of calcitonin. Sardine N-proCT has no accelerating effects on mitosis and cell differentiation of human osteosarcoma cells, as does the homologous human N-proCT. Further studies are needed to elucidate the biological activity of N-proCTs.