Motor Proteins (associated with actin filaments)

Question 1

makes muscles contract

Answer 1

myosin II

Question 2

structure in skeletal muscle made of multiculeated cells

Answer 2

fibers

Question 3

each cell from fibers contain a bundle of:

Answer 3

myofibrils

Question 4

each myofibril contains thousands of contractile units called:

Answer 4

sarcomeres

Question 5

links ECM to cytoskeleton in muscle cells

Answer 5

dystrophin glycoprotein complex

Question 6

signaling molecule in skeletal muscle

Answer 6

NOS

Question 7

muscle contraction increases levels of:

Answer 7

Ca2+

Question 8

Ca2+ increase during muscle contraction activates:

Answer 8

NOS

Question 9

activation of NOS in skeletal muscle produces:

Answer 9

NO

Question 10

caused by NO diffusion to blood vessels

Answer 10

smooth muscle relaxation

Question 11

relaxing smooth muscle causes increased:

Answer 11

blood flow to muscle tissue

Question 12

label the parts of a sarcomere

Answer 12

Question 13

thin actin filament charge type embedded in Z-disk

Answer 13

positive charge

Question 14

consists of thin filaments

Answer 14

I-band

Question 15

consists of bipolar myosin thick filaments

Answer 15

A-band

Question 16

first molecular motor identified from skeletal muscle

Answer 16

Myosin II

Question 17

this part located at myosin N-terminus

Answer 17

globular heads

Question 18

myosin globular heads at N-terminus contain:

Answer 18

force generating machinery

Question 19

myosin globular heads, light chains, and hinge region connected to:

Answer 19

coiled-coil of two alpha helices

Question 20

approach to ID functional domains within a protein is to:

Answer 20

cleave into fragments site-specific proteases

Question 21

cleaves myosin into two fragments (heavy- and light-mero-myosin)

Answer 21

Chymotrypsin

Question 22

protease cleaves HMM (heavy-mero-myosin) into subfragment 1 (S1) and subfragment 2 (S2)

Answer 22

Papain

Question 23

subfragment contains myosin head and neck regions

Answer 23

S1

Question 24

these comprise the myosin tail

Answer 24

S2 and LMM

Question 25

intrinsic ATPase activity resides in this myosin fragment

Answer 25

S1

Question 26

actin binding ability resides in this myosin fragment

Answer 26

S1

Question 27

S1 ATPase activity enhanced/activated by:

Answer 27

F-actin

Question 28

these wrap around neck region and make it more rigid

Answer 28

light chains

Question 29

type of skeletal muscle fibril can be immobilized on glass slide

Answer 29

myosin

Question 30

end of actin that myosin "walks" to

Answer 30

+ end

Question 31

actin is moved in direction of this charge on it

Answer 31

- end

Question 32

using actin movement assay, these parts of myosin can move actin

Answer 32

HMM and S1

Question 33

myosin domain determines cargo specificity

Answer 33

tail domain

Question 34

part of myosin responsible for speed of actin filament movement

Answer 34

myosin neck

Question 35

number of S1 myosin domains encoded in human genome

Answer 35

40 domains

Question 36

these myosin families are widely distributed among eukaryotes

Answer 36

Myosin I, II, and V

Question 37

all membrane associated actin filaments have this end pointed toward the plasma membrane

Answer 37

+ end

Question 38

myosin class is the only with a single head

Answer 38

class I

Question 39

myosin class binds specific receptors on organelles

Answer 39

Myosin V

Question 40

myosin class involved in organelle transport

Answer 40

Myosin V

Question 41

myosin class involved in membrane association and endocytosis

Answer 41

Class I

Question 42

type of myosin is unique because it forms bipolar filaments

Answer 42

Myosin II

Question 43

Myosin II coiled-coil tails interact with:

Answer 43

tails from other myosin molecules

Question 44

part of Myosin II points outward from myosin bundles

Answer 44

myosin head

Question 45

Myosin II bundle characteristic/property

Answer 45

bipolar "thick filaments"

Question 46

myosin head bound tightly to actin when:

Answer 46

ATP is low

Question 47

causes myosin to be released from actin filament

Answer 47

ATP binding

Question 48

results in myosin head being in "cocked state"

Answer 48

ATP hydrolysis by myosin

Question 49

myosin binding causes it to release this

Answer 49

Pi

Question 50

caused by myosin head releasing Pi

Answer 50

"power stroke"

Question 51

after power stroke the myosin head remains bound until release of:

Answer 51

ADP

Question 52

light exerts this on matter

Answer 52

force

Question 53

devise measure very small forces

Answer 53

optical trap

Question 54

optical trap uses these three parts

Answer 54

laser beam, microscope, charged bead

Question 55

optical trap charged bead attracted to:

Answer 55

intense light at center

Question 56

optical trap: force applied to particle depends linearly on:

Answer 56

displacement from trap center

Question 57

can be used to measure distance myosin molecules move actin filament each step

Answer 57

optical traps

Question 58

optical trap experiment: force can be measured by determining:

Answer 58

how much beam has to be increased to keep filament in place

Question 59

myosin type does not continuously interact with actin filaments

Answer 59

Myosin II

Question 60

name describing myosin motor that does not continuously interact with actin filaments

Answer 60

non-processive motor

Question 61

name describing myosin motor that does not release actin filament

Answer 61

processive motor

Question 62

this myosin can make many sequential steps without releasing actin filament

Answer 62

Myyosin V

Question 63

describes how long myosin is in contact with filaments for ATPase cycle

Answer 63

duty ratio

Question 64

Duty Ratio of Myosin II

Answer 64

10%

Question 65

Duty Radio of Myosin V

Answer 65

70%

Question 66

myosin type produces optical trap graph produced does not have steps

Answer 66

Myosin II

Question 67

myosin type releases ADP at slower rate

Answer 67

Myosin V

Question 68

myosin type takes clear 36nm steps, one after another

Answer 68

Myosin V

Question 69

each myosin V head moves this far

Answer 69

72 nm

Question 70

myosin type moves "hand-over-hand"

Answer 70

myosin V

Question 71

actin filament oriented with + end in:

Answer 71

Z disc

Question 72

contraction brings myosin thick filament closer to this end of actin

Answer 72

+ end

Question 73

actin filaments in sarcomere are stabilized at + end by:

Answer 73

CapZ

Question 74

actin filaments in sarcomere are stabilized at - end by:

Answer 74

tropomodulin

Question 75

protein extends along thin filament from Z-disc to tropomodulin

Answer 75

Nebulin

Question 76

consists of actin binding repeats

Answer 76

Nebulin

Question 77

length of Nebulin determines length of:

Answer 77

thin filaments

Question 78

large molecule with head in Z-disc and extends to middle of thick filament

Answer 78

Titin

Question 79

muscle contraction: action potential at neuromuscular junction travels down:

Answer 79

transverse tubule

Question 80

muscle contraction: transverse tubule continuous with:

Answer 80

sarcolemma (PM)

Question 81

muscle contraction: action potential triggers:

Answer 81

release of Ca2+

Question 82

muscle contraction: Ca2+ released from:

Answer 82

sarcoplasmic reticulum

Question 83

muscle contraction: Ca2+ induces change in long molecule strucng head to tail along thin filament

Answer 83

Tropomyosin (TM)

Question 84

muscle contraction: protein associated with each Tropomyosin (TM)

Answer 84

Troponin (TN)

Question 85

Troponin three subunits

Answer 85

TN-T, TN-I, TN-C

Question 86

without Ca2+ this blocks myosin-actin interaction

Answer 86

Tropomyosin

Question 87

Ca2+ binds to:

Answer 87

TN-C

Question 88

binding Ca2+ to TN-C triggers:

Answer 88

movement of TM (exposing actin binding sites)