Cloning of cDNA encoding a new peptide C-terminal alpha-amidating enzyme having a putative membrane-spanning domain from Xenopus laevis skin.

A cDNA clone encoding a precursor of a peptide C-terminal alpha-amidating enzyme (AE-I) from Xenopus laevis skin was recently isolated and sequenced in our laboratory. In this study, by using the restriction fragment of this clone as a hybridization probe, we have identified the cDNA encoding another new peptide C-terminal alpha-amidating enzyme (tentatively named AE-II) distinct from AE-I. The cDNA encodes a polypeptide of 875 amino acid residues, which contains a region extensively homologous to AE-I precursor at N-terminus. The encoded protein characteristically has a putative membrane-spanning domain near C-terminus. Our results indicate that C-terminal alpha-amide formation of peptides in Xenopus skin is regulated by at least two distinct alpha-amidating enzymes.