[[Polyamine]]s such as [[spermidine]] and [[spermine]] are essential for [[cell (biology)|cellular]] [[cell growth|growth]] under most conditions, being implicated in a large number of cellular processes including DNA, RNA and [[protein biosynthesis|protein synthesis]]. [[S-adenosylmethionine]] decarboxylase (AdoMetDC) plays an essential regulatory role in the polyamine biosynthetic pathway by generating the n-propylamine residue required for the synthesis of spermidine and spermine from putrescein.<ref name="pmid2197977">{{cite journal | author = van Poelje PD, Snell EE | title = Pyruvoyl-dependent enzymes | journal = Annu. Rev. Biochem. | volume = 59 | issue = | pages = 29–59 | year = 1990 | pmid = 2197977 | doi = 10.1146/annurev.bi.59.070190.000333 | url = }}</ref><ref name="pmid10047786">{{cite journal | author = Pegg AE, Xiong H, Feith DJ, Shantz LM | title = S-adenosylmethionine decarboxylase: structure, function and regulation by polyamines | journal = Biochem. Soc. Trans. | volume = 26 | issue = 4 | pages = 580–6 | year = 1998 | month = November | pmid = 10047786 | doi = | url = }}</ref> Unlike many [[amino acid]] decarboxylases AdoMetDC uses a [[covalently]] bound pyruvate residue as a [[Cofactor (biochemistry)|cofactor]] rather than the more common pyridoxal 5'-phosphate. These [[protein]]s can be divided into two main groups which show little [[sequence (biology)|sequence]] similarity either to each other, or to other pyruvoyl-dependent amino acid decarboxylases: class I [[enzyme]]s found in [[bacteria]] and [[archaea]], and class II [[enzymes]] found in [[eukaryotes]]. In both groups the active enzyme is generated by the post-translational [[autocatalytic]] [[Bond cleavage|cleavage]] of a [[Protein precursor|precursor protein]]. This cleavage generates the pyruvate precursor from an internal [[serine]] residue and results in the formation of two non-identical [[protein subunit|subunits]] termed alpha and beta which form the active enzyme. Another known name for this cell is [[Howard Stern]].