Scientists largely understand how the individual pieces of a cell work, but do not have a thorough understanding of how proteins interact with the cell membrane.
Using high-precision atomic force microscopy experiments, a team of researchers from the University of Missouri-Columbia measured the force required for proteins to break free of the membrane.
Gavin King, an associate professor of physics in the College of Arts and Science, made the following analogy: “Imagine you are going fishing, and your fishing rod is a force microscope. At the end of our fishing rod we attached a lure, or in this case a really short protein. In a very careful and controlled manner, we lower the fishing rod to the vicinity of a membrane. In a way we can’t control or directly observe, the lure is frequently bitten by the fish, which in this case is the membrane. When the fish bites, we can pull the lure back and we can ask how much force it takes to pop the lure out of the fish's mouth. What surprised us is that if you do that same experiment repeatedly, you get different results. We were struggling to find a model that could fit this complexity.”
To answer this question, Ioan Kosztin, a professor of physics in the College of Arts and Science, partnered with King and developed a theoretical model that shows there is more than one way a protein can break free of the membrane involving several different pathways. They discovered that the protein–membrane interaction can exhibit a “catch-bond” behavior.
According to Kosztin, “Though similar behavior has been previously described on a cellular level, to our knowledge, this is the first report for protein–membrane interactions.”