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SUMMARY:A 'proton ratchet' couples the membrane potential to protein secre
 tion (and perhaps also mitochondrial protein import) - Professor Ian Colli
 nson | University of Bristol 
DTSTART:20190619T140000Z
DTEND:20190619T150000Z
UID:TALK118615@talks.cam.ac.uk
CONTACT:Hannah Burns
DESCRIPTION:The proton-motive force (PMF) – the electrochemical gradient
  of protons across energy-conserving membranes – powers protein transpor
 t in bacteria\, mitochondria and chloroplasts. Here\, we propose a 'proton
  ratchet' mechanism for this process. In the Sec system of bacteria\, prot
 ons are stripped from lysine side chains of the pre-protein at the cytosol
 ic face of the plasma membrane\, then replaced on the exterior\, aided by 
 the pH component of the PMF (∆pH\; acidic outside). This gives the trans
 locating region of pre-protein a net negative charge\, allowing it to diff
 use down the electrical component (∆ψ\; positive outside). For mitochon
 drial import (through the TIM23 complex) the proton ratchet acts in the op
 posite direction\, with negatively charged residues protonated for passage
  across the inner membrane into the negative matrix. The proton ratchet is
  an elegant solution for coupling the PMF to membrane transport\, likely t
 o be used by a range of other transporters of charged molecules.
LOCATION:Sackler Lecture Theatre (Level 7) The Keith Peters Building\, Cam
 bridge Biomedical Campus
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