This is a family of S-adenosylmethionine decarboxylase (SAMDC) proenzymes. In the biosynthesis of polyamines SAMDC produces decarboxylated S-adenosylmethionine, which serves as the aminopropyl moiety necessary for spermidine and spermine biosynthesis from putrescine [1]. The Pfam alignment contains both the alpha and beta chains that are cleaved to form the active enzyme.

1: Cloning, mapping and mutational analysis of the S-adenosylmethionine decarboxylase gene in Drosophila melanogaster. Larsson J, Rasmuson-Lestander A; Mol Gen Genet 1997;256:652-660. PMID:9435790