This domain, found in various hypothetical bacterial proteins and misannotated lysozyme proteins, it has no known function. This domain contains a [S/T]GA[S/T] conserved motif and serves as a flavinylation substrate for ApbE, and is likely to be involved in extracytosolic redox activities [1].

1: Post-translational flavinylation is associated with diverse extracytosolic redox functionalities throughout bacterial life. Meheust R, Huang S, Rivera-Lugo R, Banfield JF, Light SH; Elife. 2021; [Epub ahead of print] PMID:34032212