Question

1. The figure shown here illustrates the importance of ste homology domains (SH) in cell signaling pathways. Using this figure, comment on the importance of the SH2 and SH3 domains in downstream signaling. In addition, define the functional importance of the Sos protein. Finally, please comment on potential mutations in each part of the schematic may lead to oncogenic cellular changes. plasma membrane TK Grb2 GTP P SH2 SHO SHB Ras Sos DOWNSTREAM SIGNALS

that's all I have for that questions, reason I'm so confused

Answer 1

summary:

Activation of Ras. An adaptor protein, GRB2, and guanine nucleotide-exchange factor, Sos link most activated receptor tyrosine kinases to Ras. The SH2 domain in GRB2 binds to a phosphotyrosine in activated RTKs, while its two SH3 domains bind Sos close to membrane-bound Ras GDP and activating its nucleotide exchange activity. Binding of Sos to inactive Ras causes a large confirmational change that permits release of GDP and binding of GTP, forming active Ras. GAP, which accelerates GTP hydrolysis, is localised near RasGTP by binding to activated RTKs.

Importance of SH2 and SH3 domains:

An Src Homology domain, SH2 domain, in GRB2 binds to a specific phosphotyrosine residue in the activated receptor. The SH2 domain was originally identified as a conserved amino acid sequence inthe non-catalytic region of tyrosine kinases encoded by viral oncogenes such as v-Src. GRB2 also contains two SH3 domains, which bind to and activate Sos. SH3 binds to proline-rich motifs.

please send your feedback. Thank u.