cytoplasm Flashcards

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1
Q

what sorts signals for protein translocation?

A

linear signal sequences

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2
Q

what are nuclear pore complexes?

A

they perforate the nuclear envelope (in all eukaryotes) - has 30 different proteins (nucleoporins)

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3
Q

what are unstructured proteins?

A

proteins that lack a well-structured 3d fold, form a mesh at the inner ring

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4
Q

what happens to proteins with a nucleur localization sequence?

A

they are directed into the nucleus (adding this sends it there), they have flanking basic clustersw

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5
Q

what happens to proteins with a nuclear export sequence?

A

they leave/are sent out of the nucleus

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6
Q

what are the import receptors?

A

soluble cytosolic proteins that contain multiple low-affinity binding sites for the FG repeats found in the unstrucutred domains of several nucleoporins

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7
Q

what does the importin-cargo complex do?

A

locally disolves the mesh and can diffuse in/out of NPC pore

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8
Q

what is the purpose of Ran?

A

the Ran bound to GTP provides energy and directionality

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9
Q

what are importins and exportins?

A

importins are the receptor for NLS-containing proteins, exportins are the NES receptors

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10
Q

what does GAP trigger?

A

GTP hydrolysis Ran-GDP

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11
Q

what does GEF promote?

A

the exchange of GDP for GTP

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12
Q

what do the parts of importin do?

A

the alpha subunit bind the nuclear localization signal, and the beta subunit binds the unstructured chains

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13
Q

what happens to Ran in the cytoplasm?

A

the GTP molecule inside it is hydrolyzed and the Ran dissociates, leaving importin-beta ready to carry the next cargo protein inside

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14
Q

what would happen to proteins with both NESs and NLSs?

A

they would shuttle between the nucleus and cytosol constantly

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15
Q

where are most mitochondrial proteins synthesized?

A

in the cytoplasm

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16
Q

what systems move polypeptide chains through the mitochondria?

A

TIM - translocase of inner membrane
TOM - translocates of outer membrane

17
Q

what do HSP-70 chaperones do?

A

interact with mitochondrial proteins at cytoplasm and prevent them from folding