Though well-studied, the molecular details of membrane fusion remain mysterious. In particular, scientists don't understand how holes form between two membranes, but a new study by biochemists at Rice University and Iowa State University offers intriguing new clues about the nature of this process. The study is published in this month's issue of Nature Structural and Molecular Biology.
"Membrane fusion is one of the most basic processes of life," said James McNew, assistant professor of biochemistry and cell biology at Rice University. "It begins at fertilization and occurs billions of times a second in our bodies, and if it ever stops, we die."
For example, inside the cells in our brains, spines and nerves, membranes are used to seal up and transport tiny packets of signaling chemicals from the center of the cell to the outer cell membrane. These packets, or vesicles, wait just inside the cell membrane for the appropriate signal, and once they receive it, they fuse with the membrane and eject their contents into the surrounding tissue, causing an immediate chain reaction that keeps our hearts beating and allows us to move our muscles. Membrane fusion is also used to initiate disease.
"Some invading organisms like enveloped viruses use the fusion process to infect the cell," McNew said.
To understand membrane fusion, it helps to envision the basic structure of membranes. Just five billionths of meter across, membranes are bilayers, meaning they contain two separate layers, or sheets of fatty