Heat shock proteins.
(aired on All Things Considered April 8, 2004)

If you're wondering what you should do with your life, what kind of role you want to play in society, consider becoming something like a heat shock protein. Heat shock proteins are molecules inside of cells, all kinds of cells. And, of course, we're made of cells, so heat shock proteins are everywhere in our bodies.

Cells have lots of different kinds of proteins. They make those proteins by putting together amino acids that we get from plants and animals that we eat. But to make a protein, it isn't enough to simply assemble a string of amino acids. That sequence then has to be folded into its proper shape. Proteins are three-dimensional objects made up of long folded-up strings, like those reindeers made of Christmas lights. They have to be the right shapes to do their work. And this is why heat shock proteins are important.

Proteins are supposed to self-assemble into their proper shapes, but sometimes they don't. Sometimes they fold up wrong or they stick to other proteins like tangled-up strings of Christmas lights in a box in the closet. And when they don't fold up correctly, or when they start to clump together, they can kill the cell. Heat shock proteins help other proteins fold. They hold other proteins in place long enough for them to fold properly. Some heat shock proteins even wrap around new proteins to make sure nothing else sticks to them while they fold. The heat shock protein's job is to protect and usher along other proteins. For this reason, they're also known as chaperone proteins.

When the cell starts experiencing stress, like heat or infection, new proteins have a harder time folding properly. And already folded proteins can start unfolding, and proteins start clumping together. To prevent this from happening inside the cell, the cell starts making lots of heat shock proteins to ensure that all the proteins will remain folded properly. By doing this, the cell increases its odds that it can survive a period of stress. And this is how heat shock proteins got their name. Scientists first discovered them by stressing cells with heat to learn more about how cells deal with stress.

Scientists who study the immune system have found that heat shock proteins have one more role, too. If a cell dies normally, the cell collapses in on itself and then gets engulfed and digested by other cells. But if a cell dies because of stress or injury or disease, it often explodes outwards, spilling its contents into the space around it. And those contents include lots of heat shock proteins. When heat shock proteins are outside of cells, it means that a cell has died badly. The heat shock proteins become an alarm signal to the immune system. Cells of the immune system then respond to the alarm and try to fix the problem.

So in the community of molecules in the healthy cell, the heat shock proteins help the other molecules to be what they are. In times of danger, they help the whole cell survive. And in times of disaster, they alert neighboring cells and call for help. And this is why, if you're thinking about what sort of person you want to be, I think you'd do pretty well to follow the example of the heat shock proteins.

copyright 2004 joe wright