The family includes the protease PfpI Swiss:Q51732 [1]. This domain is also found in transcriptional regulators such as Swiss:Q9RJG8.

1: Sequence, expression in Escherichia coli, and analysis of the gene encoding a novel intracellular protease (PfpI) from the hyperthermophilic archaeon Pyrococcus furiosus. Halio SB, Blumentals II, Short SA, Merrill BM, Kelly RM; J Bacteriol 1996;178:2605-2612. PMID:8626329

2: AdpA, a central transcriptional regulator in the A-factor regulatory cascade that leads to morphological development and secondary metabolism in Streptomyces griseus. Ohnishi Y, Yamazaki H, Kato JY, Tomono A, Horinouchi S; Biosci Biotechnol Biochem. 2005;69:431-439. PMID:15784968