Evolutionary shift in the site of cleavage of prelysozyme.

摘要: Sequences are presented for the signal peptides of prelysozymes from 6 species birds and compared to known sequence chicken prelysozyme c. The sequencing was done with synthetic oligonucleotides as primers oviduct mRNA template, obviating need clone DNA these species. Ring-necked pheasant c differs all other pre-alpha-lactalbumins examined by being cleaved in vivo between amino acid residues 17 18 instead 19. feature unique peptide is proline at position 17. Besides showing that acceptable carboxyl-terminal peptide, our finding implies it cannot occur penultimate peptide. This supports view unless a polypeptide has proper secondary structure, peptidase will not cleave it, this structure beta-turn. Another outcome comparative study an estimate mean rate evolution 1%/two million years divergence, similar calculated insulin Because third silent substitution rate, likely one out every three substitutions compatible function.