The cytoskeleton is an intricate network of proteins that criss-cross the cytoplasm of cells. The cytoskeleton is composed of a wide variety of proteins. These proteins often form long twisted strands that look like electrical wire or the cables used to hold up bridges. Like these man-made components, the proteins that make up the cytoskeleton are both strong and flexible.

A main fiber type, actin, is made up of long strings (polymers) of the protein actin. The image below shows the actin fibers in a cow endothelial (blood vessel) cell. The yellow colored strings are the polymerized form of the protein and the red color indicates the presence of the single protein units.


actin fibers 

Another critical cytoskeletal fiber is the microtubules. They are also polymers, and are comprised of the protein tubulin. The image below shows the microtubules in a cow endothelial cell.



As can be seen from the images above, the cytoskeleton is distributed extensively throughout cells.

The images on this page were used with the permission of the copyright owner, Molecular Probes..