Myosin

Question 1

each myosin molecule has how many heavy/light chains

Answer 1

2 heavy chains form the tail

4 light chains - 2 essential, 2 regulatory. form the motor domain

Question 2

describe the structure of myosin

Answer 2

motor domain

1 coiled coil tail

Question 3

what is the role of the motor domain of myosin

Answer 3

to bind to nt

to bind to actin

Question 4

what is the role of the tail of myosin

Answer 4

alpha helices, heavy chains….self-assemble to form the thick filament

Question 5

how do myosin molecules pack at the ends

Answer 5

parallel

Question 6

how do myosin molecules pack in the centre

Answer 6

anti-parallel, overlaps.

no cross-bridges.

Question 7

how many myosin molecules are found in ALL skeletal AND cardiac muscle cells of ALL vertebrates

Answer 7

294

Question 8

what is the length of vertebrate skeletal thick filament

Answer 8

1.6 um

Question 9

what are myosin molecule heads facing

Answer 9

the surface

Question 10

what are the myosin tails pointing to

Answer 10

the bare zone in centre (middle)

Question 11

myosin is a protein enzyme. explain why

Answer 11

myosin is an ATPase

it can slowly hydrolyse ATP

Question 12

myosin is anchored in the centre of the sarcomere in the…

Answer 12

M line

Question 13

what protein regulates the LENGTH of thick filaments

Answer 13

titin

Question 14

what is the molecular weight of titin

Answer 14

more than 3.7 Mda–> largest known protein

1 um long

Question 15

where is titin found in the sarcomere zones

Answer 15

runs from the Z-disc to the middle of the M-line

Question 16

what are other functions of titin

Answer 16

1. regulates the length of thick filament
2. organises the m-line and z-line
3. generates the resting tension