Mammalian part 2

Question 1

G-actin

Answer 1

Monomer, ADP or ATP loaded, higher incorporation at the plus-end of F-actin

Question 2

F-actin

Answer 2

Polymer, asymmetric

Question 3

Treadmilling

Answer 3

Growth at plus end and shortening at minus end of F-actin

Question 4

CapZ

Answer 4

Plus end capping, preventing growth and shortening at plus end

Question 5

Tropomodulin

Answer 5

Minus end capping, preventing growth and shortening at minus end

Question 6

Profilin

Answer 6

Promotes loading of G-actin with ATP –> growth at plus end

Question 7

Thymosin-B4

Answer 7

Binding to ATP bound G-actin–> less ATP bound G-actin available to bind to plus end –> preventing growth at plus end

Question 8

Cofilin

Answer 8

Cleaves ADP-bound G-actin –> promoting treadmilling

Question 9

Tropomyosin

Answer 9

Stiffens the filament, preventing actins to interact with other proteins

Question 10

Formin

Answer 10

Binds to G-actin molecules –> stable so it can start to grow

Question 11

small GTP-ases

Answer 11

on/off switch of the cell

Question 12

Rho

Answer 12

Small GTP-ase

Question 13

GEF

Answer 13

Switches Rho on: GDP–>GTP

Question 14

GAP

Answer 14

Switches Rho off: GTP –> GDP by hydrolysis

Question 15

Arp2/3

Answer 15

Branches growing filaments at plus end in 70 degree angle

Question 16

Cdc42

Answer 16

Activates WASP –> binding to arp2/3 + monomer –> binding to plus end –> branching and elongation of F-actin fibers

Question 17

Myosin

Answer 17

Actin motor proteins: - –> +

Question 18

Myosin 2 dimer

Answer 18

actin contraction (e.g. muscle cells)

Question 19

Stress-fiber

Answer 19

Antiparralel actin stucture, contractile bundle, contraction by myosin 2

Question 20

Cell cortex

Answer 20

Gell like network of actin

Question 21

Lamellipodium

Answer 21

Dendritic network (branched) –> extension during cell movement

Question 22

Filopodia

Answer 22

Parallel, core of bundle filaments, extrension during cell migration, regulation by small GTPase

Question 23

Integrin

Answer 23

Binds ECM and actin (transmembrane protein), adhesion of cell to ECM, regulation by small GTPase

Question 24

Microtubule

Answer 24

Composted of AB-tubulin heterodimers, stiff and difficult to bend, polar

Question 25

B-tubulin

Answer 25

Can bind to GTP or GDP, incorporation of B-tubulin to microtubule --> hydrolysis of GDP

Question 26

A- tubulin

Answer 26

GTP-bound

Question 27

MTOC

Answer 27

Microtubule organizing center

Question 28

Catastrophe

Answer 28

Shrinkage of tubule, depolarization phase, curved protofilament

Question 29

Rescue

Answer 29

Rapid growth of microfilament

Question 30

Microtubule-associated protein (MAPs)

Answer 30

protein that binds to microtubules to stabalize it, prevent binding

Question 31

Kinesin-13

Answer 31

Removal of A and B dimers

Question 32

Stathmin

Answer 32

Binds to floating filaments --> preventing growth

Question 33

EB1

Answer 33

TIP protein, stabilizes tubulin, similar to CapZ

Question 34

Kinesin

Answer 34

Anterogade movement on tubulin, toward plus end, microtubule motor

Question 35

Dyneins

Answer 35

Retrogade movement on tubulin, toward minus end, microtubule motor

Question 36

Keratins

Answer 36

Intermediate filaments in epithelia, increase tissue strength

Question 37

Vimenins

Answer 37

Intermediate filaments in connective tissue

Question 38

Neurofilaments

Answer 38

Intermediate filaments around nerve cells, Influences speed of electrical signal

Question 39

Lamins

Answer 39

Intermediate filament in nucleus, structure and organization

Question 40

Nucleation

Answer 40

Stimulating formation of new F-actin filaments