Members of this family are fusion proteins, with the N-terminal region similar to the sulfur oxidation protein SoxY (TIGR04488) and the C-terminal region similar to sulfur oxidation protein SoxZ (TIGR04490). Members occur exclusively in species with PQQ-dependent enzymes that have a Cys-Cys motif (TIGR03075) for electron transfer to c550 family cytochrome. By homology to the sulfur moiety-binding subunit SoxY, we predict the conserved Cys in the Gly-Gly-Cys motif binds some unknown adduct.
Jiyao W et al.(2023). "The conserved domain database in 2023.",