The postulated phosphorelay that results in sensing of ammonia and modulation of PKA activity to affect timing of development and the choice between slug formation versus culmination. DHKC is a sensory histidine kinase; RDEA is a histidine-containing phospho-transfer protein; REGA is the response regulator possessing activatable cAMP-phosphodiesterase activity; and PKA is cAMP-dependent protein kinase A. Upon sensing of ammonia, the histidine kinase activity of DHKC is activated such that REGA becomes phosphorylated via the phosphorelay. This lowers cAMP levels, inactivates PKA, and prevents premature terminal differentiation or promotes slug formation. ACA is adenylyl cyclase C whose regulation is not addressed here.

A more generlaized model of how the DHKC pathway is involved in various developmental regulatory phenomena can be found elsewhere.