PBIO SEMINAR SERIES

Measuring the dipole potential of a lipid bilayer by electron microscopy

Wednesday - December 14, 2005
05-06 SEMINAR SERIES
T-639

Fred Sigworth
Professor of Cellular and Molecular Physiology Yale University
Speaker's website

Host: William N. Zagotta

The interior of a lipid bilayer membrane has a large positive potential, the "dipole potential" that has important effects on membrane transport. The dipole potential has been estimated to be anywhere from 300 to 1000 mV in size, but direct measurements have not been possible. In the course of work on structure determination of membrane proteins, we developed a quantitative model of membrane images obtained in the electron microscope from cryo-EM specimens. The model doesn't work unless we include the effect of a dipole potential on the incident electrons. Fits of the model allow us to "measure" the dipole potential.