Final: Ch 18 Kinesins and Dyneins

Question 1

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

Answer 1

microtubules, ATP hydrolysis

Question 2

2 main families of motor proteins that move cargo along microtubules

Answer 2

kinesins

dyneins

Question 3

organelles in _____ are transported along microtubules in both directions

Answer 3

axons

a neuron has to supply new materials to the axon terminals

Question 4

microtubules are oriented with which end toward the axon terminal?

Answer 4

+ end

Question 5

axonal transport occurs in which direction?

Answer 5

cell body toward the axon

used chase-pulse

inject radioactive precursors and see where they end up

Question 6

anterograde transport occurs in which direction in neurons

Answer 6

cell body to synaptic terminals

associated with axonal growth and delivery of synaptic vesicles

Question 7

retrograde transport occurs in which direction in neurons

Answer 7

synaptic terminals toward the cell body along the axon

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

Question 8

what did experiments with the squid giant axon reveal?

Answer 8

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

Question 9

neurofilament movement is different why?

Answer 9

they pause frequently as they move down the axon

used GFP

Question 10

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

Answer 10

kinesin-1, anterograde, + end

Question 11

squid giant axon kinesin-1 structure

Answer 11

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

2 small tail domains

Question 12

function of kinesin head domains

Answer 12

binds microtubules and ATP

responsible for the motor activity

Question 13

function of kinesin linker domain

Answer 13

forward motility

Question 14

function of kinesin stalk domain

Answer 14

dimerization

Question 15

function of kinesin tail domain

Answer 15

binding receptors on the membranes of cargo

Question 16

assay to track kinesin vesicle movement

Answer 16

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)

Question 17

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

Answer 17

+ end, anterograde

Question 18

what kinds of functions do kinesins perform

Answer 18

organelle, mRNA and chromosome transport

microtubule sliding

microtubule depolymerization

Question 19

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

Answer 19

optical traps

fluorescent-labeling techniques

Question 20

is kinesin-1 a highly processive motor?

Answer 20

yes

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

Question 21

kinesin stepping cycle

Answer 21

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

Question 22

dynein motors transport _______ toward the __ end of microtubules

Answer 22

organelles, - end (retrograde)

Question 23

structure of dynein

Answer 23

2 large, 2 intermediate, 2 small subunits

Question 24

domains of dynein

Answer 24

2 heads

a stem

linker

Question 25

what part of dynein contains the AAA ATPase domain?

where is the stalk?

Answer 25

the head

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

Question 26

can cytoplasmic dynein mediate cargo transport by itself?

Answer 26

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

Question 27

dynactin 2 domains

Answer 27

one domain of actin-related protein Arp1 – binds cargo

CapZ caps + end

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

Question 28

what holds the 2 dynactin domains together

Answer 28

a protein called dynamitin

when overexpressed, blows apart the 2 domains

Question 29

2 major functions of dynactin

Answer 29

bind cargo

make dynein more processive

Question 30

regulation of dynein

Answer 30

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

Question 31

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

Answer 31

organelles

Question 32

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

Answer 32

MTOC, motor protein

Question 33

the golgi apparatus collects where

Answer 33

near the centrosome where the - ends of microtubules are

driven there by dynein-dynactin

Question 34

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

Answer 34

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

Question 35

the ER is spread throughout the cytoplasm by what

Answer 35

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

Question 36

organelles of the endocytic pathway are associated with which motor protein

Answer 36

dynein-dynactin

ex. late endosomes, lysosomes

Question 37

what happens when kinesin reaches the end of the microtubule

Answer 37

carried back (retrograde) on organelles transported by dynein

Question 38

______ modifications distinguish different microtubules and their accessibility to motors

Answer 38

tubulin

Question 39

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

Answer 39

post-translational modifications

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

Question 40

kinesin-1 interacts preferentially with which types of modified tubulin

Answer 40

acetylated and detyrosylated microtubules

Question 41

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

Answer 41

polyglutamylation

Question 42

does kinesin do exocytosis or endocytosis?

Answer 42

exocytosis

Question 43

does dynein do exocytosis or endocytosis?

Answer 43

endocytosis

Question 44

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

Answer 44

+ ends near periphery

• ends near nucleus

Question 45

is dynein in cilia and flagella?

Answer 45

yes, causes movement of sperm/cilia of lungs

moves damaged stuff back to cell for degradation

Question 46

kinesin-5

Answer 46

form bipolar motors that cross link antiparallel microtubules

by walking toward + ends of each microtubule, causes sliding

Question 47

kinesin-14

Answer 47

moves toward - end

mitosis