Final: Ch 18 Kinesins and Dyneins Flashcards Preview

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Flashcards in Final: Ch 18 Kinesins and Dyneins Deck (47):
1

motor proteins (kinesins and dyneins) move along _________ powered by ____ hydrolysis

microtubules, ATP hydrolysis

2

2 main families of motor proteins that move cargo along microtubules

kinesins

dyneins

3

organelles in _____ are transported along microtubules in both directions

axons

a neuron has to supply new materials to the axon terminals

4

microtubules are oriented with which end toward the axon terminal?

+ end

5

axonal transport occurs in which direction?

cell body toward the axon

used chase-pulse

inject radioactive precursors and see where they end up

6

anterograde transport occurs in which direction in neurons

cell body to synaptic terminals

associated with axonal growth and delivery of synaptic vesicles

7

retrograde transport occurs in which direction in neurons

synaptic terminals toward the cell body along the axon

transportation of old membrane from the terminals (degraded by lysosomes)

8

what did experiments with the squid giant axon reveal?

movement of vesicles along individual microtubules requires ATP

movement can move in both anterograde and retrograde directions

speed is similar to fast axonal transport in intact cells

9

neurofilament movement is different why?

they pause frequently as they move down the axon

used GFP

10

______-1 powers ________ transport of vesicles down axons toward the __ end of microtubules

kinesin-1, anterograde, + end

11

squid giant axon kinesin-1 structure

2 head domains connected by a short flexible linker domain to a long stalk

2 small tail domains

12

function of kinesin head domains

binds microtubules and ATP

responsible for the motor activity

13

function of kinesin linker domain

forward motility

14

function of kinesin stalk domain

dimerization

15

function of kinesin tail domain

binding receptors on the membranes of cargo

16

assay to track kinesin vesicle movement

vesicle or bead coated w/ kinesin-1 is added to a glass slide + microtubules

adding ATP causes movement down the microtubule in 1 direction (- to + end)

17

kinesin-1 is called a __ end-directed microtubule motor protein and transports in the _________ direction

+ end, anterograde

18

what kinds of functions do kinesins perform

organelle, mRNA and chromosome transport

microtubule sliding

microtubule depolymerization

19

what techniques were used to find out how kinesin moves down the microtubule

optical traps

fluorescent-labeling techniques

20

is kinesin-1 a highly processive motor?

yes

takes hundreds of steps by walking hand over hand down a microtubule without dissociating

21

kinesin stepping cycle

leading head binds ATP, which induces a conformational change

linker docks into the head, propelling the trailing head forward

new leading head (former trailing head) binds weakly to the microtubule and releases ADP, causing tight binding

trailing head hydrolyzes ATP --> ADP + Pi and binds weakly

22

dynein motors transport _______ toward the __ end of microtubules

organelles, - end (retrograde)

23

structure of dynein

2 large, 2 intermediate, 2 small subunits

24

domains of dynein

2 heads

a stem

linker

25

what part of dynein contains the AAA ATPase domain?

where is the stalk?

the head

btw 4th and 5th AAA subunits, contains microtubule binding region

26

can cytoplasmic dynein mediate cargo transport by itself?

no, it requires the dynactin protein to link dynein to its cargo

27

dynactin 2 domains

one domain of actin-related protein Arp1 -- binds cargo

CapZ caps + end

2nd domain of p150^glued -- dynein binding site + microtubule binding site

28

what holds the 2 dynactin domains together

a protein called dynamitin

when overexpressed, blows apart the 2 domains

29

2 major functions of dynactin

bind cargo

make dynein more processive

30

regulation of dynein

dynactin p150^glued binds +TIP EB1 so the dynein is associated with the growing + end of microtubules

this form is inactive until it reaches the cell cortex where an activator activates it

31

kinesins and dyneins cooperate in the transport of ______ throughout the cell

organelles

32

orientation of microtubules is fixed by the ______, so direction of organelle transport depends on the ____ ______

MTOC, motor protein

33

the golgi apparatus collects where

near the centrosome where the - ends of microtubules are

driven there by dynein-dynactin

34

secretory cargo from the ER is transported to the golgi by what

dynein-dynactin (b/c - end is near the golgi)

35

the ER is spread throughout the cytoplasm by what

kinesin-1 b/c + ends of microtubules are located at the periphery of the cell

36

organelles of the endocytic pathway are associated with which motor protein

dynein-dynactin

ex. late endosomes, lysosomes

37

what happens when kinesin reaches the end of the microtubule

carried back (retrograde) on organelles transported by dynein

38

______ modifications distinguish different microtubules and their accessibility to motors

tubulin

39

the stability and functions of different classes of microtubules are influenced by what

post-translational modifications

ex. acetylation of lysine in alpha-tubulin are stable, detyrosylation also increases stability

40

kinesin-1 interacts preferentially with which types of modified tubulin

acetylated and detyrosylated microtubules

41

__________ has a key role in the beating of cilia and flagella

polyglutamylation

42

does kinesin do exocytosis or endocytosis?

exocytosis

43

does dynein do exocytosis or endocytosis?

endocytosis

44

are the +, or - ends of microtubules located at the periphery of a cell?

+ ends near periphery

- ends near nucleus

45

is dynein in cilia and flagella?

yes, causes movement of sperm/cilia of lungs

moves damaged stuff back to cell for degradation

46

kinesin-5

form bipolar motors that cross link antiparallel microtubules

by walking toward + ends of each microtubule, causes sliding

47

kinesin-14

moves toward - end

mitosis