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Membranes > Ponnambalam > Flashcards

Ponnambalam Flashcards

1
Q

What are the 3 types of second messengers?

A

cAMP, PIs, Ca

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2
Q

What is the structure of PI?

A

2 fatty acids, glycerol and inositol, phosphorylated at different positions

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3
Q

What are the key domain of PLC?

A 
PH domain of 100 residues for PI
C2 for membrane in presence of Ca
SH2 for pY motifs
SH3 for PolyPro motifs
EF hands for Ca
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4
Q

What are the domain of PKC?

A

C1 for DAG
C2 for membrane
C3 for ATP
C4 for substrate

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5
Q

What class of PI3K is stimulated by RTKs?

A

1a

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6
Q

What class of PI3K are localised to the Golgi?

A

Class 2 and 3

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7
Q

Where are class 1 PI3K localised?

A

PM and Endosomes

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8
Q

Where is class 2 PI3K found?

A

Golgi and secretory vesicles

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9
Q

Where is PI4K found?

A

golgi

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10
Q

What signalling does PIP2 stimulate?

A

PLC degrades to IP3 (Ca from ER) and DAG (membrane)
Stimulates PKC for p53, Ca channels and CaM binding proteins
Primes PI3K and PDK1
directly stimulates K and TRP channels, endo/exocytosis, adhesion receptors, actin remodelling

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11
Q

What does PI3K do?

A

Convert PIP2 to PIP3 when stimulated by GPCR or RTK and RasGTPase scaffold

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12
Q

What does PIP3 stimulate?

A

Binds akt/PKB for activation by PDK1
PKB stimulates PKC, protein synthesis, cell survival, glycogen metabolism, transcription
cytoskeleton rearrangments by Rho/Rac/cdc42

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13
Q

What type of kinase is PKB?

A

Ser/thr

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14
Q

What does PLPa2 do?

A

Release fatty acids from ester bond e.g. arachidonic acid for prostaglandins, leukotrienes, PAF.
Inflammation, apoptosis

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15
Q

Where are sphingolipids derived from?

A

sphingomyelin, using DAG

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16
Q

What are the types of sphingolipid second messenger?

A

glucosylceramide
ceramide -> sphingosine, sphingosine-1-phosphate
ceramide -1-phosphate

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17
Q

what does ceramide do?

A

targets PP1/2 to counteract PKB leading to apoptosis

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18
Q

What does ceramide phosphate do?

A

Activates PLPa2

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19
Q

What does sphingosine do?

A

Interacts with PKH to control actin

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20
Q

What does sphingosine phosphate do?

A

effects immunity, inflammation and endothelial cell growth

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21
Q

What other lipid-derived compounds are there?

A

DAG -> Lysophosphatidic acids and endocannabinoids
PAF
Sphingosine 1 phosphate
Prostaglandins and Retinol can activate GPCRs and nuclear

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22
Q

What are the 5 classes of nuclear activators/ steriod hormones?

A

Mineralocorticiods, Glucocorticiods, androgens, prosgestrogens, oestrogens

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23
Q

What do retinioc acid derivatives activate?

A

rhodopsin GPCR for vision,

RAR and RXR nuclear receptors for cell differentiation and proliferation

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24
Q

What do prostaglandins/eicosaniods do?

A

PPAR: nuclear receptors for pro-inflammatory genes, GPCRS for protection of tissues, analgesia

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25
Q

What are the main families of membrane receptor?

A

Ion channels, guanylyl cyclases, GPCRs, RTK, transmembrane scaffolds

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26
Q

What are the 4 methods of signal transduction?

A

Preformed or diffusion dependant conformational coupling complexes, PTM, protein degradation

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27
Q

What are the 4 conserved signalling cascades from RTKs?

A

PI3K-PKB-proteins
Grb2-SOS-Ras-Raf-MEK-MAPK(erk)- transcription
IRS-PI3K and Ras
PLC-DAG+IP3-Calcium and P proteins

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28
Q

What do RTKs respond to?

A

Insulin and growth factors

29
Q

What structure does PDGF have?

A

symmetrical

30
Q

What RTK requires a heparin oligosaccharide to activate?

A

FGF

31
Q

What is the maximum number of ligands per RTK?

A

5

32
Q

What are the domains involved in the phosphorylation cascades?

A

SH2, SH3, PTB, PH, FYVE, FHA, WW & EVH1, PDZ

33
Q

What does FYVE bind?

A

PI(3)P

34
Q

What does FHA bind?

A

pT

35
Q

What does PDZ bind?

A

C-terminal Valine

36
Q

What domain binds Proline rich regions?

A

WW and EVH1

37
Q

How long is SH2 domain?

A

100 residues

38
Q

What sequence does SH2 bind?

A

pYXXXX

39
Q

What is the SH3 domain?

A

50 residues that bind RXXPXXP left helical poly(pro) motifs

40
Q

What domains bind pY motifs?

A

100 residue SH2 binds pYXXXX

100-150 residue PTB binds NPXpY

41
Q

How can dysregulation of RTKs cause cancer?

A

overactivation of catalytic domain

42
Q

How can RTK overactivation be treated?

A

Phosphatases counteract kinase activity, inhibit dimerisation, neutralise ligand

43
Q

What downstream effects does ERK have?

A

Transcription, PLPa2, inflammation

44
Q

What domains does an RTK have?

A

C terminal positive regulation, Juxtamembrane negative regulation, extracellular ligand binding, single TM helix, intracellular kinase

45
Q

What type of membrane protein is an RTK?

A

Type 1 integral membrane protein, inserted preformed into a signal cluster

46
Q

How are RTKs regulated?

A

Endocytosis and degradation or recycling, positive, negative and feed-forward regulation

47
Q

What is GPCR structure?

A

7TM domains, extracellular ligand binding domain and intracellular G Protein binding domain

48
Q

What is the structure of the G protein coupled to receptors?

A

a-b-y heterotrimer

49
Q

What are the 5 G protein units coupled to a receptor?

A

as, ai, aq, a1.2, by

50
Q

What does Gas stimulate?

A

Adenylate cyclase

51
Q

What does Gaq stimulate?

A

PLC

52
Q

What does Gai stimulate?

A

Blocked adenylate cyclase

53
Q

What does Ga12 stimulate?

A

GEFs for MAPK

54
Q

Are GPCR responses all-or-nothing?

A

graded response for high/low [agonist] such as adrengeric receptors

55
Q

What do GDIs do?

A

Slow spontaneous activation

56
Q

What are RGS and PLPC?

A

GAPs to inactivate G proteins

57
Q

How is protein signalling localised?

A

By scaffold proteins in membranes

58
Q

What size is the Ga subunit?

A

35-40kDa

59
Q

What size is the small soluble monomeric GTPases?

A

20kDa

60
Q

What type of membrane attachment do the small GTPases have?

A

prenylation

61
Q

Are there similarities between Ga and soluble G proteins?

A

Yes, homologous

62
Q

What are the 4 soluble GTPase families?

A

Ras
Rab(Ran)
Sar1/Arf
Rho/Rac/cdc42

63
Q

How is the soluble G protein cascade activated?

A 
Grb
SOS(GEF)
Ras
Raf
MEK
MAPK
64
Q

What does Ras do?

A

recruits Raf/HSP/14-3-3 to membrane for Src-mediated unfolding, PKC phosphorylation to activate Ser/Thr kinase activity
regulates Rho/Rac/cdc42 for actin polymerisation and dynamics to control cell shape and dynamics. Rho for FAK adhesion receptors for migration and subversion of pathogenic infection

65
Q

What do Rab GTPases do?

A

regulate membrane trafficking, with SNAREs

66
Q

Which organisms have Rab?

A

yeast and mammals

67
Q

What does Rho do?

A

Regulates FAK adhesion linked RTKs

triggers changes in actin for cell shape, migration and subversion of pathogenic reponse

68
Q

How are GTPases implicated in cancer?

A

Permanently activated in GTP form

Membranes (7 decks)

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