BIO211 Name: Sam Tian Date:
10/16/2021
Cell Communication ICA
1. Diagram a GPCR pathway involving a G-protein, adenylate
cyclase, a kinase cascade with 3 sets of kinases. The final target
protein of the pathway is a transcription factor that can enter the
nucleus when it is phosphorylated.
2. On the diagram above (using a different color pen/marker),
indicate all of the ways in which the signal transduction pathway
could be turned off.
3. Hypothesize the effects of the following mutations:
a. A mutation in the transmembrane domain of the RTK that
mediates the constant dimerization of the RTK even in the absence
of ligand.
- This type of mutation would lead to unregulated signaling pathways and
can cause cholera (leading to diarrhea and likely death if not treated).
b. A mutation in the GTP-hydrolysis activity of the Ras protein.
- A mutation in the GTP-hydrolysis activity would cause the Ras G protein to
be permanently turned “on”. The unregulated permanent activation of a G
protein can cause tumors and many different types of cancers. (A mutated
Ras protein is found in 25% of all tumors, and 90% of malignant tumors.)
