Myosin motor proteins Flashcards
How many classes are there of actin-based molecular motors?
18
What is the energy source of myosin?
Which protein polymer do they attach to?
ATP
Actin
Myosins have a conserved domain and a variable domain.
Why is the conserved domain being conserved?
The motor (head) domain is conserved.
- On one side of the head there is an actin binding site
- On the other side of the head there is a ATP (nucleotide) binding site
The non-conserved region is the tail domain. It is non conserved since it binds to other cellular proteins and needs to be different lengths based on its function.
What are the three domains of the myosin, what exists in each domain.
Tail domain: interacts with cargo proteins or lipids, determines biological function.
- attachment site to cellular proteins
Regulatory domain: Acts as a force transducing lever arm
- light chains (confer stability)
Motor domain:
- Nucleotide binding site (usually ATP)
- Actin binding site
Using optical tweezers them measured the displacement and length of displacement of beads attached to actin while being pulled on by myosin. This allowed them to determine?
The length of the displacement.
How long actin was held by myosin.
The measurements done by optical tweezers on actin filaments with myosin showed a great deal of distortion followed by periods without this distortion. Why?
Distortion is from movement of the actin, vibrating (from thermal motion) like a string. Once myosin binds it holds it steady actin you see less ‘noise’.
The length of what determines the length of the power stroke in myosin?
The length of the regulatory domain (the lever arm)
Rab-GTP is used for what?
binding of Rab-GTP to tail domain of Myosin V regulates cargo binding.
Rab GTP binds to which myosin?
Myosin five.
What does myosin five do?
IT has very long regulatory domains, so it takes massive ‘strides’ as it walks cargo across actin.
Which end does myosin five walk towards?
Myosin five walks towards the plus end of actin.
