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SUMMARY:Studying Single Molecules on living cells - Dr David Klenerman (De
 partment of Chemistry\, Cambridge)
DTSTART:20061117T110000Z
DTEND:20061117T113000Z
UID:TALK5259@talks.cam.ac.uk
CONTACT:Duncan Simpson
DESCRIPTION:One major challenge in biology is to understand how the indivi
 dual molecules and complexes of the cell are organised and interact to for
 m a functional living cell. To address this problem new biophysical tools 
 are needed. \n	One method that we have developed for functional nanoscale 
 mapping of the cell surface is based on a scanned nanopipette. This allows
  high resolution\, non-contact imaging of the soft and responsive cell sur
 face using the ion current that flows between an electrode in the nanopipe
 tte and bath for distance feedback control.1 We have used the  nanopipette
  to perform patch clamp at specific positions on the cell surface to study
  single ion channels.2 We have also combined high resolution topographic i
 maging with simultaneous recording of the fluorescence from the cell surfa
 ce.3 The pipette can be used for controlled voltage driven delivery and de
 position of biomolecules down to the single molecule level1 and this is  b
 eing used to probe the structure of the cell membrane using single molecul
 e fluorescence tracking. Recently we have made a major advance in the reso
 lution of the topographic images\, by scanning with fine quartz pipettes\,
  so we can directly visualise protein complexes on the surface of live cel
 ls. \n	To determine the oligomerisation state of proteins on the surface o
 f living cells we have used two colour single molecule coincidence detecti
 on based on the excitation of two distinct fluorophore labels on proteins 
 with two lasers focussed to the same spot.4 This method requires no prior 
 knowledge of the structure of any complex formed or control of fluorophore
  position on the molecule. We show that this method can distinguish betwee
 n protein monomers and dimers on the cell surface.  \n
LOCATION:Kaetsu Centre\, New Hall
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