BIO130H1 Lecture Notes - Lecture 19: Tamoxifen, Electron Microscope, Leading Edge

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13 Apr 2017

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The transport of nuclear proteins to the nucleus is gated and occurs through nuclear pore complexes. This is regulated by signals including hormones, calcium etc . Regulates the proteins between the cytosol and the nucleus mrna exported by the nuclear pore complex, arrives in the cytosol picked by the ribosome for translation. When translation is completed, the protein will fold in the cytosol and will shuttle through the npc"s if it has the right signal. Rnp (rna + proteins) help shuttle rna out of the nucleus. Npc"s can allow the diffusion of small molecules. When the protein is not mutated it"s found in the nucleus. When the protein is mutated (and there"s a change in the amino acid) the protein will remain in the cytosol and is prevented from entering the nucleus. Nuclear pore complex determines whether or not it can pass through. Proteins that are involved in transcription need to be moved from cytosol to nucleus.

Related Questions

2. Before nuclear pore complexes were well understood, it wasunclear whether nuclear proteins diffused passively into thenucleus and accumulated there by binding to residents of thenucleus such as chromosomes, or were actively transported andaccumulated regardless of their affinity for nuclearcomponents.
A classic experiment that addressed this problem used several formsof radioactive nucleoplasmin, which is a large pentameric proteininvolved in chromatin assembly. In this experiment, either theintact protein or the nucleoplasmin heads, tails, or heads with asingle tail were injected into the cytoplasm or into the nucleus offrog oocytes. All forms of nucleoplasmin, except heads, accumulatedin the nucleus when injected in the cytoplasm, and all forms wereretained in the nucleus when injected there.
A. What portion of the nucleoplasmin molecule is responsible forlocalization inthe nucleus?
B. How do these experiments distinguish between active transport,in which a nuclear localization signal triggers transport by thenuclear pore complex, and passive diffusion, in which a bindingsite for a nuclear component allows accumulation in thenucleus?

orangezebra695

Fill in the Blank: Transcription factors (proteins) help our cells to promote gene expression (e.g., the production of insulin) by binding directly to DNA and by assisting ______________________ to initiate transcription.

		actin monomers
		tight junctions
		RNA polymerases
		muscle fibrils

The type of GPCR (G Protein-Coupled Receptor) that can diffuse directly through nuclear pore complexes into the nucleus of our cerebellum and hypothalamus cells is called:

		CXCR₄
		ETR
		APJ
		MT₂

True or False: Some of our neurons (cells of our nervous system) have ATP-gated calcium (Ca⁺²) channels in both their plasma membrane and nuclear envelope. (tricky

True

False

1. The histones that form the core of the nucleosome get into the nucleus by which of the following?

a) Passive diffusion through nuclear pores

b) Selective and facilitated active transport through nuclear pores

c) Ribosomes located in the nucleus synthetize histones in the nucleus

d) Histones are made at the ER membrane and then diffuse to the nucleus

2. Membrane proteins that belong to the golgi, lysosome, or plasma membrane first pass through which organelle before reaching their final subcellular destination?

a) The golgi apparatus

b) The smooth ER

c) The nucleus

d) The ER membrane

e) The ER lumen

3. Where in the cell would a ribosomal protein be located if it has had its nuclear export signal inactivated (non-functional or non-existent).

a) The protein would be found in the ER lumen

b) The protein would remain in the nucleus

c) The protein would be secreted

d) The protein would remain in the cytoplasm

e) The protein would be in the ER membrane

4. Where would be the final destination of a protein if it contained a NLS anywhere in the protein sequence (and which is exposed to the cytoplasm after protein folding) but also contained an ER signal sequence at the carboxy terminus?

a) The ER lumen

b) The nucleus

c) The cytoplasm

d) The inner nuclear membrane

e) The ER membrane

5. The sequence K-D-E-L serves as a retention/retrieval signal for ER proteins.

a) True

b) False

6. The following are true for both cell membrane proteins and secretory proteins EXCEPT?

a) Precursors of the mature proteins contain signal sequence.

b) Both types of proteins contain stop-transfer sequences

c) Both types of proteins enter the ER while being synthetized

d) Both types of proteins pas through the golgi apparatus

e) Both are carried by clatherin-coated vesicles

7. If you isolate a regulated secreted protein from a secretory/storage vesicle and inject it into the cytosol, is will?

a) Be secreted through channels in the plasma membrane

b) Be taken up into secretory vesicle and secreted

c) Remain in the cytosol until it is degraded

d) Be taken up into the rough ER and follow the secretory pathway

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BIO130H1 Lecture Notes - Lecture 19: Tamoxifen, Electron Microscope, Leading Edge

BIO130H1 Full Course Notes

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