Lights, Camera, Actin 

Our cells are constantly in motion, even if they seem stationary. The movement you see in this video is a result of the dynamic nature of a structural protein called actin, which organizes into filaments that are like scaffolding for cells; actin filaments give cells their shape and contribute to their motility, or ability to move.

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Lights, Camera, Actin 

What am I looking at?

The cell shown here is an intestinal epithelial cell, with the actin protein fluorescently labeled in blue.

Biology in the background

Actin proteins assemble into thin helical filaments that form a network throughout all eukaryotic cells. This actin network is dynamic, meaning that the filaments can either grow or shrink in length to fit the structural or movement requirements of any cell. The protrusions you see growing out of and retracting back into the cell surface are supported by dense actin filaments.

Intestinal epithelial cells, like the one here, line the surface of the interior of the intestine. They perform many essential functions involved in digesting food, absorbing nutrients, protecting the body from infections, and more. In the body, they are shaped like a column; tiny, hairlike microvilli on top of the filaments stick out into the interior of the intestine, and a basal membrane on their bottom transports nutrients, water, and electrolytes to the bloodstream. In this isolated cell, you can see the role that actin plays in the creation and maintenance of the structure of the microvilli as they stick out and retract all over the surface of the cell.

Actin filaments can be up to 15 micrometers long, or roughly seven times smaller than the width of a human hair.

Technique

This video was created using confocal microscopy.