Question

1) The following cartoon illustrates a prototypical receptor tyrosine kinase cascade. Based on your knowledge of this pathway, answer the following questions that focus on the Ras GTPase enzyme and its downstream signaling. a) Complete the signal transduction cascade by filling in the empty boxes with the identities of the molecules. [4 pts] out wwwww yman Ras F Grb2) SOS b) In class, we discussed a few mechanisms that lead to amplification of the signal downstream of the RTK pathway. Name one of those mechanisms here and explain how it leads to signal amplification. [4 pts] c) Indicate how the following clinically observed mutations affect signal transduction through this RTK pathway (upregulate, downregulate, or no effect). Explain your logic with 1 sentence. [4 pts ea.] i) ii) iii) Ras Q61L: decreases intrinsic GTPase activity Ras G13D: decreases its interaction with a GAP SOS R5526: increases GEF activity on Ras

Please answer ALL questions or I'll thumbs down, thank you!

Answer 1

b)RAS BOUND GDP EXCHANGE WITH GTP CAUSES MORE ACTIVATION OF THIS PATHWAY.

THUICCuies. 14 P15] out wwwww DE Ras JapKKK) b2) SOS MAPKK ΜΑΡΚ b) In class, we discussed a few mechanisms that lead to amplification of the signal downstream of the TIAN LILI cu

G PREOTEIN CAN ACTIVATE THIS PATHWAY BY TRANSFERRING THE GTP IN PLACE OF GDP TO RAS.

C)I) RAS Q 61 L - IT WILL BE ALWAYS ACTIVATED

II) RAS G13 D- IT WILL ALSO LEADS TO MORE ACTIVATION.

III)SOS R552G-IT WILL LEADS TO MORE ACTIVATION.