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SUMMARY:Cryo-EM structures of the mitochondrial calcium uniporters - Rozbe
 h Baradaran\, Sloan Kettering Institute 
DTSTART:20180918T140000Z
DTEND:20180918T150000Z
UID:TALK109930@talks.cam.ac.uk
CONTACT:Hannah Burns
DESCRIPTION:The mitochondrial calcium uniporter (MCU) is a highly selectiv
 e calcium channel and a major route of calcium entry into mitochondria. Ho
 w the channel catalyses ion permeation and achieves ion selectivity are no
 t well understood\, partly because MCU is thought to have a distinct archi
 tecture in comparison to other cellular channels. I will be presenting the
  cryo-electron microscopy reconstructions of MCU channels from zebrafish a
 nd Cyphellophora europaea at 8.5 angstrom and 3.2 angstrom resolutions\, r
 espectively. The small molecular weight of MCU\, just approximately 110 kD
 a for the ordered region of the channel assembly\, posed challenges for st
 ructure determination by cryo-EM\, and it is one of the smallest membrane 
 proteins to have the structure determined to atomic resolution by cryo-EM.
  In contrast to a previous report of pentameric stoichiometry for MCU\, bo
 th channels are tetramers. The atomic model of C. europaea MCU shows that 
 a conserved WDXXEP signature sequence forms the selectivity filter\, in wh
 ich calcium ions are arranged in single file. Coiled-coil legs connect the
  pore to N-terminal domains in the mitochondrial matrix. In C. europaea MC
 U\, the N-terminal domains assemble as a dimer of dimers\; in zebrafish MC
 U\, they form an asymmetric crescent. The structures define principles tha
 t underlie ion permeation and calcium selectivity in this unusual channel.
LOCATION:Sackler Lecture Theatre (Level 7) Wellcome Trust/MRC Building\, C
 ambridge Biomedical Campus
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