Transcription of spoIVB is the only role of sigma G that is essential for pro-sigma K processing during spore formation in Bacillus subtilis.

Activation of pro-sigma K processing in the mother cell at late stages of sporulation in Bacillus subtilis requires the presence of active sigma G in the forespore. Placing the spoIVB gene under the control of sigma F, the early forespore transcription factor, allows sigma K to become active in the absence of sigma G. Therefore, transcription of spoIVB is the only role of sigma G that is essential for the signaling pathway between sigma G and sigma K.