Contractile Proteins Flashcards
How are actin bundles arranged?
Cross-linked actin filaments, closely packed PARALLEL arrays
How are actin networks arranged?
Loosely cross-linked in orthogonal arrays, form 3D meshwork
What is the function of actin-bundling proteins?
Small, ridged proteins that force filaments to aligned closely with each other
*Nature of association of filaments is determined by the size and shape of crosslinking proteins
What actin-binding protein is found in erythrocytes?
Spectrin
Pseudopodia
Actin filaments cross-linked into a 3D meshwork
- responsible for phagocytosis
Lamellipodia
Broad, sheet like extensions at the leading eadge of cell
Filopodia
Thin projections of plasma membrane supported by actin bundles
What are the three major domains of myosin proteins?
Head (ATP binding site)
Neck (Flexible region)
Tail (Bring myosin head regions in close proximity)
What part of the myosin protein beings with myosin light chain peptides?
Neck
In the absence of ATP, how does myosin respond to actin?
With the absence of ATP, myosin will attach to actin
If ATP binds- actin will be released (conformational change)
What state does myosin remain in until it binds to actin?
“Cocked” state
What drives the power stroke?
Release of Pi due to the binding of actin
What is the powerstroke mechanism dependent on?
Proportional to the length of neck domain!
Longer neck = increased rate of movement
During cytokinesis, what forms the contractile ring?
F-actin and myosin II
