The C signal functions after the A-signal. And it functions after 6 hours of post starvation. The C-signal is the surface protein at the poles, which binds to other receptors at the poles.
The C-signal is regulated by the Act operon.
The Act operon codes for 4 different proteins, ActA and ActB which are involved in contorl of the Act operon and ActC and ActD are involved in the timing of the csgA gene.
The product of csgA gene is CsgA, which is a 25kDa protein.
This protein is processed by a cell surface protease to a 17kDa protein. The 17kDa protein is the actual C-signal.
Increased C-signal results in activation of a cognate FruA Histidine protein kinase.
This kinase phosphorylates FruA to FruA-P.
FruA-P has two main functions. First, to activate the frz (frequency of reversal) operon and aggregation and second to activate dev operon (developnmental and sporulation genes).
