Members of this family are found in various subtilase propeptides, and adopt a ferredoxin-like fold, with an alpha+beta sandwich. Cleavage of the domain results in activation of the peptide [1].

1: 1.2 A crystal structure of the serine carboxyl proteinase pro-kumamolisin; structure of an intact pro-subtilase. Comellas-Bigler M, Maskos K, Huber R, Oyama H, Oda K, Bode W; Structure. 2004;12:1313-1323. PMID:15242607