6. Contractile Protiens Flashcards
Where do you see ATPase activity in Myosin?
In the Head region
What is a contractile ring made of?
Actin and Myosin II
What is the function of Myosin VI?
Moving vesicles towards the negative end of actin.
What actin bundling protein is present in contractile bundles?
Is this a tight or loose bundle?
Alpha-Actinin
Loose
Which end of actin does myosin move towards?
The plus end
On which end of actin do we typically see growth?
The plus end
What enzyme in smooth muscle activates myosin?
Myosin Light Chain Kinase
What actin bundling protein would you find cross linking the actin in a microvillus?
Why?
Fimbrin
Fimbrin holds actin fibers close together, which is more beneficial in a microvillus
What does the Dystrophen Gene do?
Connects Cytoskeleton to the basal lamina, stabilizes the membrane, and in so doing, helps to relieve the stress of contraction by spreading the forces out.
For Filamin:
Where are its actin binding domains located?
At the farthest ends of a dimerized structure
In a sarcomere, which side of the actin would be the plus side?
The side attached to the Z Disc
What is the function of Myosin I?
Assists with endocytosis
What causes a myosin “power stroke?”
Release of Pi
In a sarcomere which side of the actin would be the minus side?
The side farthest from the Z Disk (in the A Band)
Which myosin might you find associated with a membrane?
Myosin I
What is the basic organization of actin parallel arrays?
Actin fibers are crosslinked together with all of their plus and minus ends on the same side.
What do contractile bundles do to help a cell move forward?
They pull the plunger-like integrins off of the extracellular matrix so they don’t get stuck.
What is the function of Myosin V?
Organelle and Vescicle transport along the actin cytoskeleton.
What is filamin?
What is its function?
Actin binding protein
Creates three dimensional meshworks by binding to an actin binding domain on two different actin fibers.
What is the organizational name for actin networks’ three dimensional meshworks?
Orthogonal Arrays
What -podia are commonly associated with phagocytosis?
Pseudopodia
Erythrocytes contain spectrin:
What does it do?
Forms the actin network that makes up the cortical cytoskeleton
Where would we see an actin contractile bundle?
In muscles to assist in contraction
In the contractile ring of mitosis
What is the only myosin that moves towards the negative end of actin?
Myosin VI
Which myosin is typically associated with skeletal muscle?
Myosin II
What fiber is an essential component of pseudopodia, filopodia, and lamellopodia?
Actin
What determines the nature of the association of actin filaments?
The size and shape of the actin binding proteins
What is the heredity of Duchene’s Muscular Dystrophy?
X Linked Recessive
What will a myosin with a longer neck have over a myosin with a shorter neck?
A Myosin with a longer neck will have a greater power stroke velocity (increased rate of movement)
(Keep in mind this is not referring to the length of the tail, but the light chain neck portion)
What might be deficient in Hereditary Spherocytosis?
Cortical skeleton of the red blood cells
(More specifically, Spectrin, Ankryin, or Protein 4.1)
What facilitates cross linking of actin bundles?
Actin Bundling Proteins
Where might you find myosin light chain peptides?
In the Neck region
What contributes to the prevention of myosin binding to actin in smooth muscle?
What enzyme causes this inhibitory state?
Folding of the myosin by the regulatory light chains in the neck
Myosin Light Chain Phosphatase
