Karatekin Lab

Study how biological membranes fuse and separate. These events continuously take place in all cells as proteins and lipids are shuttled back and forth between different cellular compartments, as cells secrete compounds to their exterior via vesicle fusion with the plasma membrane, merge with one another, undergo division, or are infected by enveloped viruses such as influenza, Ebola, or HIV. Despite the enormous variety of fusion and fission reactions, only a few classes of proteins mediating these events have been discovered, suggesting that the principles that govern membrane fusion and fission reactions are general.

We are particularly interested in how neurotransmitter- or hormone-filled vesicles fuse with the plasma membrane to release their contents to the exterior of the cell, a process called exocytosis. The key proteins that constitute the exocytotic fusion machinery are well known, but how they interact with one another, lipids, and calcium that triggers fusion is not well understood. Release of neurotransmitters and hormones are tightly regulated, even after the initial narrow connection between the vesicular and the plasma membrane –the fusion pore– has been established. Using novel assays sensitive to single, nanometer-sized fusion pores with sub-millisecond time resolution, we study how exocytotic pores nucleate and how their dynamics are regulated.