University of Minnesota Duluth
University of Minnesota Department of Chemistry and Biochemistry
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Friday, February 12, 2016; 2:00 p.m.; BohH 90


Department of Chemistry & Biochemistry Welcomes:

Dr. Adam Hoppe

Associate Professor, Department of Chemistry & Biochemistry,
South Dakota State Universtiy

“A New Look at the Cell Surface: Imaging Sub-Diffraction Membrane Bending Dynamics During Clathrin Mediated Endocytosis”

All cells must constantly remodel their plasma membrane to allow the turnover of new proteins and lipids.  Endocytosis, the internalization of plasma membrane is central to broad range of key biological functions including immune response, neurotransmission, cell homeostasis and viral infection.  In this talk I will discuss our work on understanding the mechanism of clathrin mediated endocytosis (CME).
Clathrin and its auxiliary proteins drive the formation of ~100 nm sized invaginations of the plasma membrane during.  While CME has been extensively studied by electron and optical microscopy, the relationship between the ultrastructure of membrane bending and dynamics of clathrin assembly have been elusive.  In this work, we refine polarized total internal reflection fluorescence (pTIRF) microscopy to capture sub-diffraction membrane bending while imaging the recruitment of genome-edited fluorescent clathrin and dynamin to CME sites. Correlative imaging of unroofed cells by pTIRF and high-resolution transmission electron microscopy demonstrated that pTIRF is sensitive to membrane bending at all stages of the formation of ~110 nm diameter clathrin-coated pits.  The dynamic imaging from these results leads us to a new model for understanding how clathrin bends membrane during CME.