Exchanging places
Dr. Frank Visser studies the constant movement of certain substances in and out of our cells.
One of the mysteries of structural biology is how things move from the outside of a cell to the inside, and then back out again. The comings and goings of molecules and ions into and out of cells are reminiscent of the action at a busy truck stop, where big rigs pull in to refuel, then leave once their gas tanks read "full." Should a truck linger at a pump for longer than expected, chaos can result.
Cells also have a lot of action going on inside them, with many substances changing places from outside to inside and vice versa. But what makes a cell welcome these materials? And how does a cell remove the ones that have had their stay? These are questions that continue to puzzle scientists.
Dr. Frank Visser, an AHFMR-supported post-doctoral fellow at the University of Calgary, is one of those scientists. In the lab of AHFMR Scientist Dr. Jonathan Lytton, he has been helping unravel the mystery of how calcium moves into and out of cells. When you consider that calcium triggers vital functions in the body-heartbeats, hormone secretion, and communication from brain cells-you have to acknowledge that it's important work.
Much is already known about how cells move calcium and other nutrients in and out. For example, a certain family of proteins present in a cell membrane play critical roles in the transport of calcium. Called sodium/calcium (Na+/Ca2+) exchangers, these proteins keep the amount of calcium entering a cell in check. Once the maximum permitted quantity of calcium is inside a cell and has gone to work signalling a muscle contraction or some other important response, the exchange system must function properly to regulate the strength and duration of that response. When something goes wrong with the exchange system, a serious problem can arise-possibly heart failure or stroke.
Dr. Visser concentrates on the structural and functional properties of sodium/calcium exchange systems. In particular, he studies a type of exchanger that is important for vision, learning and memory, and skin pigmentation. We know that, in such exchanges, potassium ions as well as calcium ions are excreted from the cell. However, we don't know which ions leave first, or why.
To study the exchange process more closely, Dr. Visser uses SURFE2R technology -instrumentation that can detect even the slightest difference in electric charge on delicate isolated cell membranes, and measure that difference with a degree of accuracy not previously attainable. Because the charge moving across a cell membrane is so very weak, it is important to use equipment of the highest sensitivity in this research.
After 10 year in the academic research field, Dr. Visser has moved to the next stage of his career. He recently accepted a post as a research scientist with SemBioSys, a Calgary-based firm that produces proteins of pharmaceutical importance.