GAPES2 (GAmmaproteobacterial PEriplasmic Sensor) domain is a periplasmic sensor domain found in diguanylate cyclases, including the diguanylate cyclase DgcI (YliF) of Escherichia coli [1]. It contains three conserved Cys residues that might participate in thiol-disulfide exchange.

1: Systematic Nomenclature for GGDEF and EAL Domain-Containing Cyclic Di-GMP Turnover Proteins of Escherichia coli. Hengge R, Galperin MY, Ghigo JM, Gomelsky M, Green J, Hughes KT, Jenal U, Landini P; J Bacteriol. 2015;198:7-11. PMID:26148715