#Question id: 1246
#Unit 4. Cell Communication and Cell Signaling
An SH2-containing protein contains a mutation that changes its binding pocket such that tyrosine and phosphotyrosine bind with equal affinity. As a result, MEK activity:
#Question id: 1247
#Unit 4. Cell Communication and Cell Signaling
Which of the following is NOT true about the role of adapter proteins in the activation of Ras by receptor tyrosine kinases?
#Question id: 1248
#Unit 4. Cell Communication and Cell Signaling
By what mechanism does PI-3 phosphate promote activation of protein kinase B (PKB)?
a. recruiting PKB to the plasma membrane
b. recruiting the activating kinase PDK1 to the plasma membrane
c. releasing inhibition of the catalytic site by the PH domain
d. by the activation of FOXO3A
#Question id: 1249
#Unit 4. Cell Communication and Cell Signaling
As in all G protein–coupled signalling pathways, timely termination of the rhodopsin signalling pathway requires that all the activated intermediates be inactivated rapidly, restoring the system to its basal state, ready for signalling again. Which of the following mechanism does not terminate rhodopsin signalling?
#Question id: 1250
#Unit 4. Cell Communication and Cell Signaling
Few mutants (column A) and their results (column B) are listed in the table given below:
|
Column A |
Column B |
|
A. Gain-of-function of Ski |
I. Inhibits the ability of activated type I TGF-β receptors (RI) to phosphorylate R-Smad proteins |
|
B. Loss-of-function of RII receptor |
II. Transcription activation induced by TGF-β and mediated by Smad complexes is shut down |
|
C. Gain-of-function of smad-7 |
|
|
D. Loss-of-function of R-smad |
Match the correct mutation with the observe result?
#Question id: 1251
#Unit 4. Cell Communication and Cell Signaling
Following statements are regarding to receptor serine kinases.
A. The two serines in each Smad3 that were phosphorylated by the RI receptor kinase bind to phosphoserine-binding sites in the MH1 domains of a Smad3 or a Smad4, forming a stable complex containing two molecules of phosphorylated Smad3 (or Smad2) and one molecule of the co-Smad (Smad4).
B. The bound importin then mediates translocation of the heteromeric R-Smad/co-Smad complex into the nucleus.
C. After importin dissociates inside the nucleus, the Smad3/Smad4 (or Smad2/Smad4) complex binds to other transcription factors to activate transcription of specific target genes.
D. Transcription of the PAI-1 gene requires formation of a complex of the transcription factor TFE3 with the R-Smad/co-Smad (Smad3/Smad4) complex and binding of all these proteins to specific sequences within the regulatory region of the PAI-1 gene.
E. Within the nucleus, R-Smads are further modified by phosphorylation of their linker domains, monoubiquitinylation of their MH1 domains, acetylation of their MH2 domains, and dephosphorylation of the C-terminal serines by nuclear phosphatases.
Which of the following combination is incorrect?