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Cards In This Set
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How is the cytoplasmic side of the nuclear envelope supported?
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By Intermediate Filaments (vimentin IF's) and it is studded with ribosomes
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How is the inner membrane of the nuclear envelope supported?
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By nuclear lamina (lamin IF's)
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Regarding the Nuclear Pore Complex (NPC), what makes its structure?
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 1.) Nucleoporins made of glycoproteins of NPC2.) Cytoplasmic Ring: 8 subunits each with a cytoplasmic filament (Ran Binding protein- nuclear transport)3.) Luminal Ring: 8 transmembrane proteins connecting the nucleoporins to the membrane |
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What kind of transport is involved in the NuclearPoreComplex?
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Bidirectional:-Passive when about 9nm-Selective active transport for Macromolecules a.) Imports proteins (histones, polymerases, TF's) and snRNP's b.) Exports mRNA, tRNA, and ribosomes |
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Specify nuclear import for Nuclear Pore Complex (NPC) traffic
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 -Translocation of protein complexes through NPC requires energy from hydrolysis of GTP mediated by Ran GTP-ase -Cargo protein contains Nuclear Localization Signal (NLS-address label) -Importin- imports receptors in the cytosol. Binds NLS and nucleoporins: in the nucleoporins: Imports |
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Specify nuclear export for Nuclear Pore Complex (NPC) traffic
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 -Translocation of protein complexes through NPC requires energy from hydrolysis of GTP mediated by Ran GTP-ase -Cargo protein contains Nuclear Export Signal (NES) -Exportin: (export receptors in nucleus) binds NES & Nucleoporins: Exports |
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Regarding Import/Export traffic of the NPC, what is the small G protein that is involved with the G Protein cycle?
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 Ran. Its conformation and activity is regulated by GTP binding and hydrolysis (Ran/GTP or Ran/GDP) |
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What is required in regards to the Ran gradient in order to import proteins through the nuclear pore complex?
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A high concentration of Ran/GDP in the cytoplasm and a high concentration of Ran/GTP in the nucleus.
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For NPC traffic, when is the ran complex considered to be switched "on"?
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 Once it is bounded to GTP Guanidine nucleotide exchange factor (GEF) exchanges GDP for GTP. |
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For NPC traffic, when is the ran complex considered to be switched "off"?
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Once it is bounded to GDP Ran GTPase-activating protein (Ran GAP) Hydrolyzes GTP to GDP |
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What would it mean if Ran-GEF (Guanidine nucleotide exchange factor) were present in the nucleus?
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This would tell us that there are high levels of GTP present in the nucleus
-Ran-GEF exchanges GDP-->GTP |
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What are the players of NPC import?
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Cargo Protein which bind to alpha/beta importin -When bound there is interaction w/ nucleoporins and translocates the complex inside -Once there is interaction with Ran-GTP, importin releases its cargo protein and Ran-GTP-importin returns to the cytoplasm -Ran-GAP (GTPase activating protein) hydrolyzid RanGTP-->RanGDP and realeases importin... Importin can now pick up more cargo |
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How is mRNA transported from the nucleus to the cytoplasm?
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 RNA's (mRNA, tRNA, and rRNA) are transported across the NPC as RNA-Protein complexes: Heterogeneous nuclear ribonucleoproteins (hnRNP's) |
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How are Viruses introduced to the cell?
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Viruses transport themselves within the cell by using our own import complex.
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What is responsible for the round shape of the nucleus?
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Lamin a, b and c
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