(This question has two parts, I don\'t know how to break them up because they ar
ID: 36264 • Letter: #
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(This question has two parts, I don't know how to break them up because they are based off of each other, because of this I will increase points but please don't close my question because I need both questions together!)
5. You are interested in how proteins are imported into and eported out of the nucleus. For your experiment you use several mutant cell lines or treat normal cells with abnormal conditions. You examine 2 different proteins - protein A is 100 kD and protein is 25 kD. Both proteins have both an NLS and an NES. Neither NLS or NES is ever masked.
a) In Mutant 1 you can inactivate all Ran-GEF. You wait until the loss of Ran-GEF function results a steady state for Ran-GEF attached molecules. You then induce this mutant to start tranlating protein A. Where will protein A be found in these cells? EXPLAIN
(This question has two parts, I don't know how to break them up because they are based off of each other, because of this I will increase points but please don't close my question because I need both questions together!) 5. You are interested in how proteins are imported into and eported out of the nucleus. For your experiment you use several mutant cell lines or treat normal cells with abnormal conditions. You examine 2 different proteins - protein A is 100 kD and protein is 25 kD. Both proteins have both an NLS and an NES. Neither NLS or NES is ever masked. a) In Mutant 1 you can inactivate all Ran-GEF. You wait until the loss of Ran-GEF function results a steady state for Ran-GEF attached molecules. You then induce this mutant to start tranlating protein A. Where will protein A be found in these cells? EXPLAIN b) Instead of using a mutant cell line, this time you incubate normal cells so that they have an excess of GTP S in both the cytosol and nucleus. GTP?S is a GTP analog that behaves exactly like GTP except that it cannot be hydrolyzed. You then induce these cells to start translating protein A. Where will protein A be found in these cells? EXPLAINExplanation / Answer
A nuclear localization signal or sequence also called as an NLS is an amino acid sequence that 'tags' a protein for import into the cell nucleus by nuclear transport. Typically, this signal consists of one or more small sequences of positively charged lysines or arginines expressed on the protein surface. Different nuclear localized proteins may share the same NLS. An NLS has the opposite function of a NES- nuclear export signal, which targets proteins out of the nucleus.
A nuclear export signal is also known as an NES amino acid, this is a short amino acid sequence of 4 hydrophobic residues in a protein that targets it for export from the cell nucleus to the cytoplasm through the nuclear pore complex using nuclear transport. It has the opposite effect of a nuclear localization signal, which targets a protein located in the cytoplasm for import to the nucleus. The NES is recognized and bound by exportins.
RAN-Guanine Nucleotide Exchange Factors (GEFs) are also proteins involved in the activation of small GTPases. These small GTPases act as molecular switches in intracellular signaling pathways and have many downstream targets. The most well-known GTPases comprise the Ras superfamily and are involved in essential cell processes such as cell differentiation and proliferation, cytoskeletal organization, vesicle trafficking, and nuclear transport. GTPases are active only when bound to GTP and inactive when bound to GDP, allowing their activity to be regulated by GEFs and the opposing GTPase activating proteins (GAPs). when the GEFs are inactivated by mutation, this makes translation impossible. this mutant protein A will be transported by the NLS and NES respectively as their translation will be carried out in the cytosol by the cell organells translational mechanism. thus the protein a wil be present in the cytosol.
b. here the protein A will be present in the Nucleusitself as the GTPase is functionan translation wil happen as usual in the nucleus and be imported and exported by the NES and NLS.
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