Gated Transport Flashcards

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1
Q

newly synthesized proteins must ____ properly and undergo various ______

A

fold, modifications

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2
Q

what does it mean when a protein is folded co-translationally?

A

folded immediately as proteins are synthesized

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3
Q

what is a molten globule?

A

quick formation of an approximate secondary structure from the almost there state

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4
Q

what are molecular chaperones?

A

proteins needed to assist in protein folding

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5
Q

what is HSP?

A

heat shock protein, they help proteins fold and shield hydrophobic patches (can get messed up if exposed to water)

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6
Q

what is HSP60 and HSP70

A

HSP70 then HSP60
HSP70- associates as a polypeptide emergence?
HSP60- barrel like structure that holds unfolded proteins helps it refold

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7
Q

what happens to proteins that are not properly folded?

A

try to refold correct but if not gets degraded

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8
Q

how do you know when a protein is properly folded?

A

does not have hydrophobic patches

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9
Q

what is a proteasomes?

A

for protein degradation, many copies in cytosol and nucleus, stack of 4 rings, central core where degradation occurs and caps that gate for proteins marked for degradation

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10
Q

what is the polyubiquitin chain?

A

marks a protein to be degraded, gets recognized by proteasome cap

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11
Q

what is ubiquitination?

A

putting a ubiquitin onto a protein

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12
Q

what is the E2/E3 complex (ubiquitan ligase)?

A

puts a ubiquitin onto the bad protein

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13
Q

what is E2 (ubiquitin-conjugated enzyme)?

A

holds onto ubiquitin thats gonna be put onto protein.

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14
Q

what is E1?

A

ubiquitin activating enzyme. takes in ubiquitin and interacts with E2 to put it on

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15
Q

whats an additional function of ubiquitin?

A

DNA repair, endocytosis, histone regulation, regulate protein function

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16
Q

what are prion diseases?

A

2 ways to fold a protein (good and bad), bad influences the good to change shape and they are resistant to degradation

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17
Q

what are FG repeats?

A

line nuclear pore complex, unstructured, permeability to large molecules, and act as a docking site for nuclear cargo receptors.

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18
Q

what is the nuclear localization signal?

A

tag on a protein that says it needs to go in/out of nucleus, has + charged residues from arg and lys, can be located anywhere on protein, binds to nuclear import receptors/ nuclear import adaptor proteins

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19
Q

what is gtp hydrolysis?

A

GTP turns into GDP, phosphate group leaves

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20
Q

what are g-proteins?

A

protein that can bind to GTP

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21
Q

describe ran mediated nuclear import/export

A
  1. an active G-protein will undergo GTP hydrolysis which turns the GTP into GDP
  2. the g-protein is now inactive and the GDP will leave
  3. another GTP will come and attach to the g-protein turning it active again
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22
Q

what is GTPase?

A

enzymatic activity that hydrolyzes GTP to GDP

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23
Q

what is guanine nucleotide exchange factor?

A

kicks GDP off of g-protein, only exists in the nucleus. binds to chromatin

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24
Q

nuclear import receptor only binds to ____ not ____

A

GTP, GDP

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25
Q

describe ran mediated nuclear import with the receptors (hard version >:) )

A
  1. nuclear import receptor binds to a protein with nuclear localization signal (cargo) and goes into the nucleus
  2. nuclear import receptor delivers cargo to nucleus and ran-gtp binds to it
  3. nuclear import receptor goes back to the cytosol and GTP turns into GDP and nuclear import receptor lets go and starts the process over
26
Q

nuclear export receptor can only bind to cargo if its also bound with ___

A

ran-GTP

27
Q

nuclear export/import receptor can go ____ ____ in nuclear pore complex

A

both ways idk they dumb

28
Q

describe ran mediated nuclear export with the receptors (hard version >:) )

A
  1. nuclear export receptor goes through nuclear pore complex and binds with ran-gtp and cargo in nucleus
  2. nuclear export receptor goes to the cytosol where ran-GAP transforms GTP into GDP and it lets go of both ran-GDP and cargo
29
Q

what is the point of ran-GEF?

A

makes sure theres another ran-GTP in nucleus

30
Q

what is the ER signal sequence?

A

1 or more + charged AA sequence next to 6-12 hydrophobic residues (core)

31
Q

what is co-translational translocation?

A

directs new protein to ER membrane as it is being synthesized

32
Q

what is post-translational translocation?

A

fully translated when transferred

33
Q

what are the rough patches on the ER?

A

ribosomes doing translation

34
Q

what is signal-recognition particle?

A

recognize ER signal sequence, temporarily stops translation. binds to SRP-receptor on surface of ER

35
Q

describe ER translocation

A
  1. ribosome binds to SRP causing a pause in translation
  2. SRP binds to SRP receptor of ER
  3. SRP and its receptor are released
36
Q

what does a closed translocator look like?

A

plug is..plugged in

37
Q

what does an open translocator look like?

A

signal peptide binds to it. plug moves and the growing polypeptide chain will go through.

38
Q

where does translation take place if the protein is needed in the cytosol?

A

cytosol

39
Q

what are soluble proteins?

A

proteins not transmembrane, completely soluble in the lumen of ER, secreted to the outside of cell

40
Q

what is signal peptidase?

A

enzyme on ER membrane that cleaves off ER signal peptide

41
Q

what are transmembrane proteins?

A

has to work on a membrane has to cross and stay in membrane

42
Q

what is internal ER signal sequence?

A

binds to translocator. translation occurs.

43
Q

what is stop transfer sequence?

A

hydrophobic region of protein. stops translation

44
Q

what happens if the + AA are before hydrophobic core?

A

embedded in end terminus in cytosol?

45
Q

what happens if the + AA are after hydrophobic core?

A

embedded in the terminus of ER

46
Q

what is a multipass transmembrane protein?

A

mix of start end transfer sequence, protein goes in and out of membrane

47
Q

will a protein that is going to be secreted have a stop transfer sequence?

A

its not sticking in membrane. has to go to ER

48
Q

what proteins wouldn’t go to ER?

A

cytosolic proteins, histones,

49
Q

what are post-translational translocation?

A

complete proteins going in membrane

50
Q

what is glycosylation?

A

carbohydrates attached to proteins. begins in ERs and into golgi

51
Q

what are the 2 ways to link oligosaccharides?

A

n-linked and o-linked glycosylation. trimming and processing needed. is a timer to see how long the proteins been there

52
Q

when is retrotranslation apparatus needed?

A

protein is modified but hasnt progressed. something is wrong with protein and is degraded

53
Q

what is the process of retrotranslation apparatus

A

protein translocator recognizes and transfer protein into cytosol. E3 ubiquitin marks for degradation. proteasome degrades misfolded protein

54
Q

what type of translocation does mitochondria use?

A

post-translational translocation

55
Q

post-translational translocation are relatively ______

A

unfolded

56
Q

what is TOM complex?

A

translocator of outer mitochondrial membrane

57
Q

what is TIM (22/23) complex?

A

translocator of inner mitochondrial membrane

58
Q

what is SAM complex?

A

translocator of outer mitochondrial membrane

59
Q

what is OXA complex?

A

translocator of inner mitochondrial membrane. used when proteins go into matrix but are needed for inner membrane

60
Q

describe how matrix proteins get into mitochondria

A

mitochondrial translation signal recognized by TOM complex. pushed through TlM complex. signal peptide gets cleaved by signal pepidase.

61
Q

describe how inner membrane proteins get in mitochondria

A

mitochondrial translation signal recognized by TOM complex. doesn’t go through TIM. signal peptide cleaved.

62
Q

what happens when a protein goes through a TOM complex but not TIM?

A

protein goes into inner membrane space through TOM and chaperones help you fold.