Single-molecule imaging and tracking of molecules in the plasma membrane of living cells are now providing researchers with the unprecedented ability to directly observe and analyze molecular dynamics and interactions in/on the cell membrane. One of the most exciting results the speaker has recently obtained is that signaling in/on the plasma membrane is often enabled by molecular complexes of signaling molecules and scaffolding proteins that are rapidly exchanging with those located in the bulk cytoplasm and the bulk plasma membrane, rather than stable molecular complexes and the solid-state-like circuits they produce, at variance with the prevalent views shown in many cell-biology and biochemistry textbooks and reviews.
About the speaker
Prof. Akihiro Kusumi received his DSc in Biophysics from Kyoto University in 1980. He furthered his research career in the Medical College of Winconsin and Princeton University and was appointed as an Assistant Professor by Kyoto University in 1984. He joined the faculty in the University of Tokyo in 1988 and the Nagoya University in 1997, and returned to Kyoto University as a Professor in 2005. In 2017, he moved to the Okinawa Institute of Science and Technology Graduate University and is currently a Professor there.
Prof. Kusumi’s research focuses on capturing single molecule dynamics at 40,000 frames/sec, which allowed him to propose an explanation for the reduced diffusion speed of proteins in the membrane. This model called the “hop diffusion” model, revolutionized and furthered the idea of lipid rafts. Using colloidal gold tags he was able to see short time confined movements inside GPI-anchored receptor clusters showing that rafts may confine molecules transiently and not block molecular movement across regions of the membrane. This new finding changed the thinking about how the cellular signaling system works.
Prof. Kusumi received numerous awards including the Excellence Award at the 52nd Science and Technology Film/Video Festival, Japan (2011), the Excellency Prize at the 14th TEPIA High-Tech Video Competition (2004), the Ministry of Education Award at the 45th Science and Technology Film/Video Festival, Japan (2004) and the Setoh Award by the Japanese Society for Microscopy (2002).
