This family includes the N-terminal non-catalytic domains from creatinase and prolidase. The exact function of this domain is uncertain.

1: Enzymatic mechanism of creatine amidinohydrolase as deduced from crystal structures. Coll M, Knof SH, Ohga Y, Messerschmidt A, Huber R, Moellering H, Russmann L, Schumacher G; J Mol Biol 1990;214:597-610. PMID:1696320

2: Structure of the prolidase from Pyrococcus furiosus. Maher MJ, Ghosh M, Grunden AM, Menon AL, Adams MW, Freeman HC, Guss JM; Biochemistry. 2004;43:2771-2783. PMID:15005612