Inside each living cell is a complex system of roadways, each used to transport molecules so the cell can keep performing the processes it was made to do.
Like highways that span from one state to another, cells can even use the roadways to deliver molecules to other cells.
How cells are able to do this has been an intense area of study for years, and thanks to three Nobel Prize-winning scientists, it’s a little more understood now.
This year’s Nobel Prize for Physiology or Medicine was awarded to scientists who have unraveled the mysteries of how cells route or traffic specific molecules to the correct locations.
The $1.4 million prize was split among Drs. James Rothman of Yale University, Randy Schekman of University of California-Berkeley and Thomas Sudhof of Stanford University.
Their work revealed a basic element of cell physiology that is essentially the same for all cells, from single-celled yeasts to complex mammals like humans.
The basic mode of transporting molecules in cells is in a vesicle — hollow, spherical structures that carry molecules inside.
Molecules are packaged at different places in cells and then safely transported at the right time to the correct destination via vesicles.
But how does this transportation container know where to drop off its delivery?
With mail, a ZIP code is written on the outside of a letter specifying a precise location where it is to be delivered.
With vesicles, there are specific proteins on the outside surface of the sphere that specify where its cargo is to be delivered, whether it’s within a cell or to the cell’s surface, to be released from the cell to other cells.
With the right cellular ZIP code, molecules are delivered to the right place.
Schekman discovered the genes and proteins that regulate these vesicles. They are the traffic cops that control vesicle traffic through the cells.
He found that different genes and proteins determined whether a vesicle delivered its contents to the cell’s surface or to different compartments inside a cell.
While he studied this in yeast cells, similar genes and proteins have been found in more complex animals such as mice and humans.
Rothman found the specific proteins on the surfaces of vesicles that represent molecular ZIP codes and allow the vesicles to interact with proteins at their correct destinations.
The interaction between these two groups of complementary proteins causes the vesicle to fuse with the membrane at its intended destination and release its contents.
Sudhof revealed how nerve cells communicate with each other and how calcium ions control this activity. He found that calcium ions act as a trigger, causing vesicles to fuse with cell surfaces and release the molecules to interact with neighboring cells, transmitting signals along a nerve.
This transportation system is used for critical functions in humans, like brain signals and immune responses, so problems within the system can cause disease.
These pioneers have provided an incredible understanding upon which others can continue to build.