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z:Cell 300 > Lecture 18: Protein Lipidation > Flashcards

Lecture 18: Protein Lipidation Flashcards

1
Q

protein lipidation (def.)

A

a covalent modification of proteins by lipids

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2
Q

protein lipidation can play a key role in _____ and _____ of modified protein

A

localization and function

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3
Q

most modifications are ___ but some can be ____

A

stable (permanent)
dynamic (regulated addition and removal)

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4
Q

protein lipidation promotes localization in membrane by ____

A

acting as an anchor in membrane

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5
Q

protein lipidation can be ___ or ____

A

co-translational
post-translational

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6
Q

Five main categories of Protein Lipidation

A

1) glypiation
2) cholesteroylation
3) prenylation
4) Acylation
5) Other

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7
Q

glypiation is the addition of _____

A

GPI anchor

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8
Q

cholesteroylation is the addition of _____

A

cholesterol

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9
Q

prenylation is the addition of _____

A

farnesyl and geranylgeranyl

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10
Q

acylation is the addition of _____

A

fatty acids (myristate and palmitate)

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11
Q

other types of protein lipidation is the addition of _____

A

phospholipids

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12
Q

several proteins are subject to _____ because it promotes _____

A

multiple lipidation
strong association with membrane

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13
Q

nature of lipidation affects ___ and ____

A

localization and properties

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14
Q

5 main lipids

A

1) myristate
2) palmitate
3) palmitoleic
4) farnesyl
5) geranylgeranyl

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15
Q

protein lipidation with myristate linkage? to associated residue? stability?

A

amide/H2N-Gly –> stable

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16
Q

protein lipidation with palmitate linkage? to associated residue? stability?

A

thioester/cysteine –> dynamic
amide/ H2N-Cys –> stable

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17
Q

protein lipidation with palmitoleic linkage? to associated residue? stability?

A

oxyester/serine –> stable

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18
Q

protein lipidation with farnesyl linkage? to associated residue? stability?

A

thioether/cysteine –> stable

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19
Q

protein lipidation with geranylgeranyl linkage? to associated residue? stability?

A

thioether/cysteine –> stable

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20
Q

2 saturated lipids

A

1) myristate
2) palmitate

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21
Q

3 unsaturated lipids

A

1) palmitoleic
2) farnesyl
3) geranylgeranyl

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22
Q

cholesterol can be ___

A

inserted into membrane

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23
Q

protein cholesteroylation helps with ____

A

protein insertion into membrane

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24
Q

main targets for protein cholesteroylation are ___

A

protein of the Hedgehog family (Hh)

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25
Q

Hedgehog protein family (def.)

A

family of secreted signaling proteins needed for growth and patterning

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26
Q

Hedgehog protein family are morphogens that can ____

A

elicit developmental fate over significant
distances

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27
Q

Hedgehogs are produced as ______ and large extension at ______

A

larger precursors with signal sequence
the C-terminus

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28
Q

Hedgehogs require ____

A

extensive processing

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29
Q

Cholesteroylation of Hh proteins method

A

1) cleavage in conserved Gly-Cys-Phe (GCF) on C-terminus after translocation
2) auto-processing mediated by C-terminal extension
3) Transfer of cholesterol to C-terminal glycine
4) Stable palmitoylation at N-terminus on Cys

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30
Q

Both the _____ and _____ (protein lipidation) are essential for function of Hh proteins

A

cholesteroylation
stable palmitoylation

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31
Q

the protein modifications of Hh proteins allows the ____

A

secreted signaling domain to remain tethered to PM

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32
Q

the protein modifications of Hh proteins help the protein to form____

A

micelles

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33
Q

Protein isoprenylation occurs on _____

A

cysteine residue part of the “-CAAX” or “-CXC” motifs at the C-terminus
(A-aliphatic residues)

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34
Q

Protein isoprenylation forms ___ bond

A

Irreversible thioether

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35
Q

Isoprene has how many carbons?

A

5

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36
Q

Farnesyl residue has how many carbons?

A

15

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37
Q

geranylgeranyl residue has how many carbons?

A

20

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38
Q

General rule: when to add geranylgeranyl vs farnesyl residue?

A

-geranylgeranyl: CAAX, CXC –> X = leucine (L)
- farnesyl: anything else

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39
Q

the synthesis pathway of cholesterol contains ____

A

many lipids used in protein lipidation as intermediates

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40
Q

Protein isoprenylation of small GTPases is needed for ___

A

attachment to membrane

41
Q

Geranylgeranylated proteins display ____affinity for membranes (especially ___)

A

high
di-geranylgeranylated proteins

42
Q

geranylgeranyl group is _____ than farnesyl group

A

10-40X more hydrophobic

43
Q

Some prenylated proteins (____) must be extracted from membranes by ____

A

Rabs
specialized chaperones (GDIs, Guanine nucleotides dissociation inhibitors)

44
Q

GDI keeps protein bound to ___

A

GDP

45
Q

fatty acylation with ___ and ____ acts to mediate ____

A

myristate and palmitate
special types of membrane targeting

46
Q

fatty acylation uses how many types of fatty acids?

A

3; all saturated but of different lengths

47
Q

3 types of fatty acids for fatty acylation

A
  • C8:0, octanoate (ghrelin etc…)
  • C14:0, myristate
  • C16:0, palmitate
48
Q

fatty acylation increases protein ___ and promotes _____

A

hydrophobicity
weak membrane interaction

49
Q

myristate (# carbons?)

A

14

50
Q

palmitate (# carbons?)

A

16

51
Q

____% of human proteome is myristoylated

A

~0.5%

52
Q

N-myristoylation adds ____

A

myristate co-translationally to N-terminal
glycine

53
Q

enzyme needed for N-myristoylation?

A
  • N-myristoyl transferase I (Nmt I)
54
Q

Nmt I is associated with ___

A

ribosome

55
Q

Nmt I transfers ___ following removal of ____

A

myristate
initiating methionine

56
Q

N-myristoylation bond formed?

A

amide bond

57
Q

N-myristoylation stability?

A

Stable (not reversible)

58
Q

N-myristoylation often works with ____ to regulate membrane association

A

second signal

59
Q

S-Palmitoylation is typically added _____ to _____

A

post-translationally to thiol group of specific cysteine residue

60
Q

S-Palmitoylation stability?

A

Reversible, dynamic

61
Q

Most common lipid modification

A

Protein Palmitoylation

62
Q

S-Palmitoylation is easily detectable because ____ which is cleavable with ____

A

it involves a thioester bond
hydroxylamine

63
Q

S-Palmitoylation is typically used to ____

A

regulate protein function

64
Q

S-Palmitoylation happens what type of protein?

A

many different types of proteins

65
Q

S-Palmitoylation happens on what residue? near what?

A

usually Cys residue close to membrane surface, sometimes near myristoyl or prenyl group

66
Q

proteins with this domain acts as palmitoyl acyltransferases (PATs) in many organisms?

A

DHHC-domain (zDHHC containing proteins)
aspartate-histidine-histidine-cysteine

67
Q

Glypiation occurs when? stability? targets? function?

A

-post-translational
-stable
- extracellular proteins
- targets proteins to rafts

68
Q

Cholesteroylation occurs when? stability? targets?

A

-post-translational on newly exposed C-terminal glycine
-stable
- found on members of hedgehog family

69
Q

Isoprenylation occurs when? stability? targets? function?

A
  • post-translational on cysteine within -CAAX, -CCAAX or -CXC
    -stable
    -promotes membrane recruitment and further processing
70
Q

-N-palmitoylation occurs when? stability? targets? function?

A
  • post-translational on N-terminal cysteine
  • found on members of hedgehog family
  • stable (amide bond)
71
Q

-N-myristoylation occurs when? stability? targets? function?

A
  • co-translational on N-terminal glycine of cytosolic protein
  • stable (amide bond)
72
Q

*S-palmitoylation occurs when? stability? targets? function?

A

-post-translational on cysteine, various positions
- thioester bond cleavable with hydroxylamine
- reversible/dynamic (thioester bond)

73
Q

Cancer cells often increase the expression of _____

A

N-myristoyltransferase

74
Q

PCLX-001 treatment results in _____

A

the degradation of N-myristoylated proteins

75
Q

PCLX-001 selectively ____

A

kills blood cancer cells in vitro

76
Q

PCLX-001 induces cells death by _____

A

triggering apoptosis

77
Q

composition of lipids in organelles depends on ___

A

what organelle it is?

78
Q

Synthesis of lipid is ____ in the cells.

A

location-specific

79
Q

Final steps in the synthesis of phospholipids (eg. PC) are catalyzed by _____

A

membrane-bound enzymes on the cytosolic surface of the endoplasmic reticulum

80
Q

Cholesterol synthesis is completed _____

A

on the ER membrane

81
Q

Addition of headgroups to ceramide to produce glycosphingolipids (sugar) or sphingomyelin (choline) occurs ______

A

on the lumenal face of cis and trans-Golgi membranes

82
Q

Trans-bilayer movement (flip-flop) of charged lipids is _____ in artificial liposomes

A

extremely slow

83
Q

Generation of Membrane Asymmetry at ER membrane

A

Phospholipids synthesized on cytosolic side of ER membrane are transferred to lumenal leaflet by a scramblase (maintains
equilibrium across bilayer)

84
Q

Membrane Asymmetry at ER membrane? ATP?

A

ATP independent

85
Q

Scramblase at PM action? stimulated by? ATP?

A

-moves lipids in both directions
-simulated by calcium
-ATP independent

86
Q

movement of amino-phospholipids at PM action? stimulated by? ATP?

A
  • PS and PE moved from outer to inner leaflet by specific flippase
    -creates asymmetry
    -ATP dependent
87
Q

floppase works at ___ and is responsible for ____

A

PM
export of lipids from the cell

88
Q

floppase action? ATP?

A

moves phospholipids from inner to outer leaflet at PM
ATP hydrolysis promotes activity

89
Q

floppase best characterized as a member of ______ protein family

A

ABC (ATP-binding cassette)

90
Q

Membrane asymmetry critically controls _____

A

transmembrane protein function

91
Q

Movement of ____ from the ______ to other
compartments relies on ______

A

sphingolipids
Golgi complex
vesicle-mediated transport

92
Q

Phospholipids and cholesterol can move between organelles by ______

A

different mechanisms that do not involve vesicles

93
Q

Phospholipids and cholesterol movement to cell surface? speed? ATP?

A

extremely rapid movement to cell surface
- ATP-independent

94
Q

drug that block COPI function

A

BFA

95
Q

transport of phospholipids and cholesterol is not eliminated by ____

A

BFA (drug that blocks COPI - vesicle transport)

96
Q

mechanism for transport of phospholipids and cholesterol involves____

A

Lipid Transfer Proteins (LTPs)

97
Q

proteins CERT and ORP5 do what?

A

create unique interorganelle contact sites to facilitate exchange of specific lipids

98
Q

phospholipids, ceramide and cholesterol transport involves ___ and/or ______

A

specific transfer proteins
inter-organelle membrane contact sites (MCS)

z:Cell 300 (17 decks)

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