Podcast
Questions and Answers
What is the primary function of the Nuclear Pore Complex (NPC) in eukaryotic cells?
What is the primary function of the Nuclear Pore Complex (NPC) in eukaryotic cells?
- To facilitate passive diffusion of small molecules
- To recycle GDP to the nucleus
- To actively transport macromolecules out of the nucleus (correct)
- To synthesize proteins and RNA
Which signal sequence is necessary for proteins to be exported from the nucleus?
Which signal sequence is necessary for proteins to be exported from the nucleus?
- Nuclear Localization Signal (NLS)
- Nuclear Export Signal (NES) (correct)
- Cytochemical Signal (CCS)
- Cytoplasmic Retention Signal (CRS)
What role does Ran-GAP play during the active nuclear export process?
What role does Ran-GAP play during the active nuclear export process?
- It stabilizes the exportin-cargo complex
- It hydrolyzes GTP into GDP (correct)
- It promotes the binding of exportin to NES
- It assists in the recycling of Ran-GTP back to the nucleus
How is Ran-GDP transported back to the nucleus after it dissociates from the exportin?
How is Ran-GDP transported back to the nucleus after it dissociates from the exportin?
In which part of the cell is Ran-GEF situated, and what is its primary function?
In which part of the cell is Ran-GEF situated, and what is its primary function?
What would happen if a cargo protein lacked a Nuclear Export Signal (NES)?
What would happen if a cargo protein lacked a Nuclear Export Signal (NES)?
What determines the specificity of exportins for different cargo proteins or RNA?
What determines the specificity of exportins for different cargo proteins or RNA?
During the export process, which molecule is involved in stabilizing the exportin-cargo complex?
During the export process, which molecule is involved in stabilizing the exportin-cargo complex?
Flashcards
Nuclear Export
Nuclear Export
The process of moving molecules (proteins or RNA) from the cell nucleus to the cytoplasm.
Nuclear Pore Complex (NPC)
Nuclear Pore Complex (NPC)
A complex of proteins that forms channels through the nuclear envelope, enabling transport of molecules between the nucleus and cytoplasm.
Nuclear Export Signal (NES)
Nuclear Export Signal (NES)
A specific amino acid sequence on a protein that signals its need for export from the nucleus.
Exportins
Exportins
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Ran-GTP
Ran-GTP
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Ran-GDP
Ran-GDP
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Ran-GAP
Ran-GAP
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Nuclear Transport Factor 2 (NTF2)
Nuclear Transport Factor 2 (NTF2)
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Study Notes
Active Nuclear Export
- Anything produced in the nucleus and needed in the cytoplasm is exported via the Nuclear Pore Complex (NPC).
- Small molecules diffuse passively, but macromolecules (e.g., proteins, RNA) require active transport.
- This process uses nuclear pore complexes (NPCs) and is energy dependent.
Ran-GTP Cycle and Export Process
- Ran is a GTP-binding protein crucial for transport.
- Ran-GDP is inactive and found in the cytoplasm.
- Ran-GTP is active and found in the nucleoplasm.
- Ran-bound exportins are unable to associate with exportin unless it contains a GTP molecule.
- Exportins are nuclear transport receptors, which bind to the NES (Nuclear Export Signal) on cargo proteins or RNA.
- The exportin, cargo, and Ran-GTP complex move through the NPC and into the cytoplasm.
- Ran-GAP in the cytoplasm hydrolyses GTP to GDP, causing Ran to release the cargo, and exportin returns to the nucleoplasm.
- Ran-GDP is recycled back into the nucleus via NTF2(Nuclear Transport Factor Two).
- The Ran-GTP cycle (GDP to GTP to GDP) keeps the process active.
Components
- Nuclear Pore Complex (NPC)
- Exportin (nuclear transport receptor)
- Nuclear Envelope
- Ran
- Ran-GTPase Activating Protein (Ran-GAP)
- Ran-GEF (Ran Guanine Nucleotide Exchange Factor)
- Nuclear Export Signal (NES)
- Cargo (protein or RNA)
Location of Components
- Ran-GTP is concentrated within the nucleoplasm.
- Ran-GDP is concentrated within the cytoplasm.
- Exportins are located within the nucleoplasm.
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