Image origins: That walking molecule
Suddenly it’s everywhere: a gif of a molecule stepping along, carrying a big load.
It’s currently going viral online, with text suggesting that it’s a myosin molecule carrying endorphins in the brain.
It’s none of that.
First of all, it’s not a myosin molecule, but kinesin. They’re both motor proteins and some of the myosin proteins have a very similar function as kinesin, but this one is definitely kinesin. There are some myosin molecule that can carry cargo like that (like myosin Va), but they look a little bit different. Myosin Va has longer “legs”; kinesin has its “feet” very close together.
It’s also not “in the brain”. This is an artistic representation of how it would look like in a cell, but it’s not in any particular type of cell. It’s comparable to someone drawing a general picture of a house: without further detail, it would just be “a house”, not “a house in England” or “a house in my street”. Likewise, saying that this is a brain is just a bit too specific. There’s nothing to suggest it is. Just like the drawing of a house, we can’t see much of the surroundings because they were deliberately not included in the picture. If you’re asked to draw a house, you draw only the house, not the whole street. A real cell is very crowded inside, not an empty cavernous space like this, but this scene is representative of one thing that happens inside any busy cell.
And finally, that’s not necessarily a “bag of endorphins”, but just a general vesicle. A lot of different kinds of molecules are transported within cells, and many of them are carried in vesicles, especially if they are meant to end up either in the cell membrane or outside of the cell’s environment. So it could be carrying endorphins (which act on receptors on the outside of cells) but it could also be lots of other things. There’s just no way to tell, since the artist only represented the outside of the vesicle, and the chemicals it carries inside would be too small to see at this magnification anyway.
It’s great that a cell biology animation is going viral online (because motor proteins are amazing!) but unfortunate that the information that comes with it is not entirely correct, and that the artist doesn’t get the credit for this brilliant piece of work.
This is not a video made with a microscope – it’s an animation that someone made. Specifically, it was created by John Liebler of Art of the Cell, who initially animated the kinesin molecule for the 2006 video The Inner Life of the Cell.
This GIF is also by him. It’s not identical to the shot in the video, but made in a similar style. On his blog he describes a bit of the history of the animation.
“The kinesin motor protein was a real scene stealer in Inner Life, although it wasn’t even in the original treatment for the short. The original plan was to omit the motor protein in the vesicle shots, but when I saw Graham Johnson’s animation of the way a kinesin takes a step from April 2000(…), I secretly went ahead and modeled one of my own”
So that’s where that image came from! It’s much more than just endorphins in the brain, and it was a brilliant piece of work by a professional science animator.