Posted: May 25, 2010

Monitoring protein function in vitro by lipid nanotubes

(Nanowerk News) Dr. Joshua Zimmerberg, senior investigator of the National Institutes of Health, USA visited the Institute of Biophysics (IBP) at the Chinese Academy of Sciences and delivered a lecture at the invitation of IBP director Professor XU Tao on May 20, 2010.
Presided by Professor XU, Dr. Zimmerberg’s presentation was titled "Proteins as constraints on topology to drive action at a distance". He first discussed scientific significance and role of dynamin, an essential component of vesicle formation in receptor-mediated endocytosis, synaptic vesicle recycling, and caveolae internalization. He showed that by inserting its domain to the membrane, dynamin provides energy to bend the membrane curvature that facilitates vesicle fission process. This novel aspect of dynamin had been published in Cell in 2009.
Through monitoring dynamin’s function in vitro by lipid nanotubes (NT), his group discovered how GTPase dynamin protein was involved in membrane fission during endocytosis. By measuring the conductance of the NT, they found that dynamin was capable of squeezing itself to extremely small radii, depending on the NT lipid composition.
Dr. Zimmerberg later discussed GLUT4, an insulin regulated glucose transporter which can translocate to the cell surface under the stimulation of insulin. Using FPALM (a single molecular method), his group detected the recruitment of GLUT4 single molecular in cell membrane. They also calculated the cluster size which coupled with clathrin dependent endocytosis.
Dr. Joshua Zimmerberg is Chief of both the Laboratory of Cellular and Molecular Biophysics and the Section on Membrane and Cellular Biophysics in the National Institute of Child Health and Human Development, USA. His research interests encompass studies of molecules, membranes, viruses, organelles and cells to understand viral and parasitic infection, exocytosis and apoptosis, with a particular focus on membrane fusion, fission and poration. Among his many achievements, Zimmerberg was the first researcher to demonstrate the existence of the fusion pore, the role of lipids in the apoptotic pore formed by Bax, and the pathway of biological membrane fusion.
Source: Chinese Academy of Sciences