Abstract
Similar conserved structures appear in apparently unrelated protein families. Thus,
the superfamily of insulin shows an evolutionary relationship with the α-conotoxins
of marine fishhunting snails as indicated by methods of protein comparison. In order
to reach statistical significance, the A-chains of different insulins, insulin-like
growth factors, relaxins, insulin related peptides from invertebrates were drawn for
comparison. These data were correlated with sequences from randomly chosen proteins.
The α-conotoxins show identity scores up to 37.5% and similarity up to 56.2% toward
the members of the insulin-superfamily. These scores conform to values achieved by
comparing the relaxin and the insulin/IGF-sequences. The data show clearly that the
identity and similarity values obtained in the comparison with the insulins are significantly
higher than the scores of randomly chosen protein primary structures. According to
our calculated data, this hormone system regulating metabolism and growth in vertebrates
and the mentioned toxin-receptor system share the same evolutionary ancestor. However,
this statistical approach has to be substantiated on gene level.
Key words
Insulin-Superfamily - α-Conotoxins - Evolution
