Activation of Ras by Grb2-SOS: Demonstrating an Assembly Role of SH3 Domains

The animation shows a schematic representation of the assembly role of SH3 domain-containing proteins using Grb2 as an example. Growth factor stimulation leads to the activation of receptor tyrosine kinases and to the phosphorylation of the receptor tail and the stimulation of phosphorylation of related adaptor proteins (not shown). The resultant phosphotyrosines form docking sites for the adaptor protein Grb2 (through its SH2 domain). The Grb2 SH3 domains bind proline-rich motifs in SOS, the guanine nucleotide exchange factor for Ras, recruiting SOS to the membrane and colocalizing it with Ras. The resultant stimulation of Ras activates a mitogen-activated protein kinase cascade, leading to cell growth and differentiation. The animation could be useful in demonstrating how different protein domains allow dynamic regulation of protein activity, protein assembly, and protein recruitment, allowing cells to respond to signals from their extracellular environment. [Resource Details]