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Blebbistatin is a drug that specifically inhibits the assembly of myosin in the cytoskeleton. What effect would you expect blebbistatin to have on intracellular vesicles?

The formation of vesicles would cease.
The movement of vesicles within the cell would cease.
The vesicle membranes would fail and release their contents into the cytoplasm.
The vesicles would be unable to fuse with the plasma membrane.

I don't readily see how Blebbistatin would effect intracellular vesicles; I believe this ignorance comes from not knowing what myosin is and how it interacts in the cytoskeleton.

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    $\begingroup$ What textbook are you reading from? $\endgroup$
    – James
    Jun 8 '16 at 3:12
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Blebbistatin inhibits myosin II by blocking it's attachment with actin. Myosin II and other actin based motors have shown to be involved in vesicle budding from trans golgi network. Given this information, I think correct answer will be

The formation of vesicles would cease.

Following cartoon from (Stow et al 1998) shows proposed mechanism,

enter image description here

However looking at this paper, option (2) The movement of vesicles within the cell would cease, also sounds reasonable.

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    $\begingroup$ Option 2 is correct. Vesicles do not need cytoskeleton for their formation (it is dependent on, among others, structural proteins like COP-I/II and clathirin). $\endgroup$
    – WYSIWYG
    Feb 8 '16 at 11:54
  • $\begingroup$ @WYSIWYG: Kinesins and dyneins do transport vesicles, and are not affected by blebbistatin. www.ncbi.nlm.nih.gov/books/NBK21710/‎ $\endgroup$
    – Joce
    Sep 6 '16 at 12:40
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Blebbistatin blocks effectively the Myosin II light chain kinase (MLCK)activity, and myosin being a motor protein, plays an important role in vesicle traffciking thereby affecting the process of endo and exocytosis. With this information, I think it would be logical to say that blebbistatin will cease the formation of vesicles, the vesicle movement and inturn will inhibit the ability to fuse with the plasma membrane. It looks to me more like a cumulative effect of blebbistatin on the intracellular vesicles.

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    $\begingroup$ Vesicle formation would not be inhibited. $\endgroup$
    – WYSIWYG
    Feb 8 '16 at 11:56

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