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CBIO3400 > Microtubules > Flashcards

Flashcards in Microtubules Deck (57):
1

chemical property of microtubules

polarized

2

microtubules oriented with + ends toward:

plasma membrane

3

microtubules oriented with - ends towards:

centrosome

4

4 functions of microtubules:

mitosis, transport, motility, signaling

5

microtubules are composed of these subunits

alpha- and beta- tubulin dimers

6

each MT tubulin monomer can bind:

1 GTP

7

GTP bound to this tubulin is physically trapped at dimer interface and is never hydrolyzed or exchanged 

alpha-tubulin

8

tubulin type can bind either GTP or GDP

beta-tubulin

9

one tubulin MT subunit consists of:

tubulin heterodimer

10

tubulin heterodimers assemble linearly to form:

protofilament

11

13 protofilaments form:

microtubule

12

structure of microtubule

hollow tube

13

drug stabilizes MTs

Taxol

14

drug binds and stabilizes actin filaments

Phalloidin

15

drug caps filament plus ends and destabilizes microfilaments

Cytochalasin

16

drug severs actin filaments

Swinholide

17

multiple subunits associating laterally important for allowing cytoskeletal filaments to:

resist breakage

18

for assembly of MTs, tubulin concentration must be:

above Cc

19

for MTs to depolymerize, tubulin concentration must be:

below Cc

20

end that tubulin alpha-beta-dimers add more rapidly

+ end

21

Preferred end for assembly is the  (+) end, in which this tubulin is exposed

beta tubulin

22

Cc is lower at this MT end

+ end

23

GTP bound to beta-tubulin hydrolyzes during

polymerization

24

Free energy from hydrolysis is transferred to polymer, making dissociation of this form of tubulin more energetically favorable

D-form

25

soluble tubulin subunits are in this form

D-form

26

MTs have GTP cap at this end

+ end

27

Cc is when:

on rate = off rate

28

this tubulin subunit form has higher affinity for GTP-tubulin

T form

29

this tubulin form has higher Cc

D form

30

dissociation of subunits preffered on this end at intermediate concentration

- end

31

dissociation of tubulin dimers is favored at this end because Cc T is lower than intermediate concentrations

+ end

32

name for MT movement in live cells

treadmilling

33

to visualize treadmilling, small amount of this injected into cell

rhodamine conjugated tubulin

34

describes the assembly, catastrophe, disassembly, and rescue of MTs

dynamic instability

35

dynamic instability depends on:

GTP cap

36

GTP cap removal from + in results in reduced affinity for:

Tubulin-GTP (T form)

37

during this stage of dynamic instability, subunits lost from + end and local tubulin subunit concentration increases

dissasembly

38

during this stage of dynamic instability, free tubulin-GTP reaches Cc of D form 

rescue

39

these proteins stabilize MTs

MAPs

40

3 types of MAPs

tau, MAP2, MAP4

41

MAPs bind:

charged wall of MT

42

MAP type found only in dendrites

MAP2

43

MAP type forms fibrous cross-bridges between MTs and links to IFs

MAP2

44

MAP type is present on both dendrites and axons

Tau

45

MAPs are regulated by:

phosphorylation

46

these control MAP activity

MARK/Par-1 and CDK

47

cell with overexpression of this MAP have larger diamer and MTs more spaced apart

MAP2

48

these proteins bind to the + end of MTs

+TIP

49

MT protein binds seam at + end and acts as "weld"

EB1

50

proteins enhance MT catastrophes by enhancing GTP hydrolysis at + end

Op18/Stathmin

51

inactivates Op18/Stathmin

phosphorylation

52

organizes MTs throughout the cell

centrosome

53

centrosome consists of:

two centrioles and pericentriolar material

54

pericentriolar material contains:

gamma-TURC (Tubulin Ring Complex)

55

serves as nucleation site for MT filaments

gamma-TURC

56

centrosome (MTOC) is located at:

center of cell (near nucleus)

57

gamma-TURC located at this end of MT

- end