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. 2023 Jan 6;480(1):1–23. doi: 10.1042/BCJ20220234

Figure 4. Dynamic RAS regulation by GEFs and GAPs.

Figure 4.

(A) RAS immobilized on microbeads is used to study the effects of GEFs and GAPs on RAS activation as measured by the recruitment of a labeled RAF1-RBD. (B) A positive feedback that recruits more GEF (RBD-RasGRF) to beads as more RAS is activated amplifies weak input signals under high GAP conditions. (C) The allosteric feedback whereby RAS:GTP binds to and activates SOS reduces overshoot in the output dynamics. Panels (A–C) are adapted from [52]. (D) Feedback regulation of SOS and NF1. Green arrow, activation; red blunt-end lines, inhibition.