CellSig4 - 27 Flashcards Preview

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Flashcards in CellSig4 - 27 Deck (27):
1

Characterise small GTPases

Small monomeric 21kDa proteins with intrinsic GTPase activity that can bind to and hydrolyse GTP

2

What modifications do many GTPases have?

Lipid modifications to target them to specific membrane sites

3

What family do small GTPases belong?

Ras

4

What region of the small GTPase is most important?

Switch region alters the protein resulting in its activation when bound

5

Outline the activation/deactivation cycle of small GTPases

Active (quick GTP hydrolysis) > inactive (slow removal of GDP) > inactive (quick GTP association)

6

What inactivates GTPase?

GAP - GTPase activating protein

7

What activates GTPase?

GEF - guanine nucleotide exchange factor

8

What sequesters GDP proteins for GTPase?

GDI - guanine nucleotide dissociation inhibitor

9

What is Arf?

ADP ribosylation factor - controls general aspects of membrane trafficking

10

What is Rab?

Ras-like in brain - regulation of vesicle trafficking, docking and sorting

11

What is Ran?

Ras-like nuclear - controls nuclear import and nuclear export

12

What is Ras?

Ras sarcoma - master regulator of cell growth and survival

13

What is Rho?

Ras homology - maintains cell structure and polarity

14

What is imperative in regulation of Arf family proteins?

Localisation of GEF

15

What is key to specificity of vesicle targetting?

GEF and GDI

16

Outline the distribution of Ran across the nuclear membrane

Ran-GTP inside, Ran-GDP outside nucleus

17

How is the Ran distribution maintained?

Ran-GEF in nucleus, Ran-GAP and RanBP outside

18

What does RanGTP do?

Targets empty importins to the cytosol

19

What does RanGTP do once in the cytosol?

Dissociates from importin, hyrdolysed to RanGDP and is imported

20

What does MAP stand for?

Mitogen activating protein

21

Outline the Ras pathway

Active Ras > MAP k.k.kinase (Raf) > MAP k.kinase (Mek) > MAP kinase (Erk) > internal changes

22

Name 3 Rho family GTPases

RhoA, Rac1 and Cdc42

23

What do Rho family GTPases do?

Coorfinate actin cytoskeletal organisation

24

What does RhoA do?

Stabilises and consolidates actin filaments into more rigid framework known as stress fibres

25

What does Rac1 do?

Organises new actin filaments into fynamic ruffling structures or lamellipodia

26

What does Cdc42 do?

Polymerises actin filaments and forms actin spijes or filopodia

27

What is a CRIB domain?

Cdc42/Rac1 Interaction/Binding domain