/
Flashcards from Upload
Save to my account
Sign up
Flashcards from Upload
mTORC1 and Protein Synthesis Regulation
Study
1
Question
What is the primary function of mTORC1 in cellular metabolism?
Answer
Regulates anabolic processes, including protein synthesis, in response to nutrients.
2
Question
How does mTORC1 influence protein synthesis downstream?
Answer
By phosphorylating targets like S6K and 4E-BP1.
3
Question
What initiates transcription of DNA into RNA?
Answer
Assembly of the preinitiation complex at the TATA-box.
4
Question
What role does the 5'-end cap play in mRNA?
Answer
Stability, translation initiation, and ribosome recruitment.
5
Question
Describe the process of RNA splicing.
Answer
Removal of introns catalyzed by spliceosomes.
6
Question
What are the three sites on eukaryotic ribosomes for tRNA binding?
Answer
A-site, P-site, and E-site.
7
Question
How is translation initiation completed in eukaryotes?
Answer
By recruiting the 60s subunit after the start codon is recognized.
8
Question
What is required for elongation to begin in translation?
Answer
Binding of aminoacyl-tRNA to the A-site via eEF1A-GTP.
9
Question
Which codons signal termination of translation?
Answer
UAA, UAG, UGA.
10
Question
What enzyme catalyzes the formation of peptide bonds during elongation?
Answer
The ribosome catalyzes peptide bond formation.
11
Question
How does eEF2 facilitate the elongation cycle?
Answer
By translocating tRNAs from A and P sites to P and E sites.
12
Question
What are the main pathways mediating protein degradation?
Answer
Ubiquitin-proteasome system and lysosome-mediated breakdown.
13
Question
How does ubiquitination target proteins for degradation?
Answer
Ubiquitin is attached to proteins marked for breakdown.
14
Question
What role do lysosomes play in protein degradation?
Answer
Degrade proteins via autophagy or endocytosis within acidic organelles.
15
Question
What are the core components of mTORC1?
Answer
mTOR, Raptor, and mLST8/GβL.
16
Question
How does rapamycin inhibit mTORC1?
Answer
By forming a complex with FKBP12, sterically hindering substrate access.
17
Question
What is the function of Raptor in mTORC1?
Answer
Regulates substrate binding for phosphorylation by mTOR.
18
Question
What are the main upstream pathways activating mTORC1?
Answer
PI3K/Akt pathway and RAS/RAF/MEK/ERK pathway.
19
Question
How do growth factors activate mTORC1?
Answer
Through PI3K leading to Rheb activation.
20
Question
What is the role of Rheb in mTORC1 activation?
Answer
GTP-bound Rheb stimulates mTOR kinase activity.
21
Question
How does Akt regulate Rheb activity?
Answer
By inhibiting the TSC complex, which normally inhibits Rheb.
22
Question
What is the primary role of Rheb in mTORC1 activation?
Answer
Active Rheb-GTP stimulates mTORC1 kinase activity.
23
Question
How does Akt promote mTORC1 activation?
Answer
By inhibiting TSC2, which suppresses Rheb.
24
Question
What is the function of the TSC complex in mTOR regulation?
Answer
It acts as a GAP, inhibiting Rheb by promoting GTP hydrolysis to GDP.
25
Question
How do amino acids regulate mTORC1 localization?
Answer
AA sensing proteins like SLC38A9 and Rag GTPases translocate mTORC1 to lysosomes.
26
Question
What is the role of GATOR1 in amino acid signaling?
Answer
GATOR1 acts as a GAP inhibiting RagA/B, suppressing mTORC1 activity.
27
Question
How do growth factors influence Rheb activity?
Answer
GF signaling inhibits the TSC complex, allowing Rheb activation.
28
Question
What is the significance of PRAS40 in mTORC1 regulation?
Answer
PRAS40 inhibits mTORC1; PI3K/mTORC1 activity causes its dissociation.
29
Question
Describe the crosstalk between the Ras/ERK and PI3K/Akt pathways in mTORC1 regulation.
Answer
ERK phosphorylates TSC2 and Raptor; PI3K/Akt inhibits TSC2; pathways synergistically activate mTORC1.
30
Question
How does FAK contribute to mTORC1 activation?
Answer
FAK binds and activates PI3K, and phosphorylates TSC2, stimulating mTORC1.