Figure 2.

Representative Golgi-based signalling pathways. Several signalling complexes have been shown to be present on intracellular organelles. Here we depict the main elements of four representative pathways: the IgE receptor (IgEr) on the PM activates PKC, which promotes the recruitment of ARF1 and COPI to the Golgi complex via an unknown mediator. This pathway regulates the transport of cargo toward the PM. A hypothetical receptor (R?) with a potential intracellular location activates Gα_s that, in turn, activates adenylyl cyclase, to generate the cAMP that is necessary for activation of PKA at the Golgi complex. This active PKA phosphorylates the KDELr, uncovering the COPI-binding motif that is necessary for its retrograde transport. A hypothetical receptor (R?) activates a heterotrimeric G protein to release its βγ subunit. This generates diacylglycerol (DAG) through an unknown mechanism, which in turn activates PKCη. The subsequent phosphorylation and activation of PKD is required for membrane fission at the TGN. Stimulation of the EGF receptor (EGFr) produces via PLCγ the Ca²⁺ and DAG that are necessary for translocation of the Ras exchange factor Ras-GRP1 to the Golgi complex. Ras-GRP1 activates Ras on the Golgi, and the resulting activation of the MAP kinase (MEK/ERK) pathway supports basic cellular functions, such as cell growth and differentiation.