Figure 1. Regulation of signal output from receptor tyrosine kinases.

(a) Signaling is controlled by the activities of tyrosine kinases, tyrosine phosphatases, and effector proteins that can bind to tyrosine-phosphorylated sites. (b) The amount of signal output is proportional to the amount of effector complexes, which in turn depends on the rates of phosphorylation and dephosphorylation, and the local concentration and affinities of effectors.