Members of this family comprise the Firmicutes lineage endospore formation-specific sigma factor SigG. It is also desginated stage III sporulation protein G (SpoIIIG). This protein is rather closely related to sigma-F (SpoIIAC), another sporulation sigma factor. [Transcription, Transcription factors, Cellular processes, Sporulation and germination]
Lu S et al.(2020). "CDD/SPARCLE: the conserved domain database in 2020.",