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CATEGORIES:Electronic Structure Discussion Group
SUMMARY:The transport mechanism of mitochondrial carriers 
 based on an analysis of symmetry - Edmund Kunji (M
 RC Mitochondrial Biology Unit)
DTSTART;TZID=Europe/London:20091104T113000
DTEND;TZID=Europe/London:20091104T120000
UID:TALK15870AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/15870
DESCRIPTION:The structures of mitochondrial transporters and u
 ncoupling proteins are threefold pseudosymmetrical
 \, but their substrates and coupling ions are not.
  Thus\, deviations from symmetry are to be expecte
 d in the substrate and ion-binding sites in the ce
 ntral aqueous cavity. By analysing the threefold p
 seudosymmetrical repeats from which their sequence
 s are made\, conserved asymmetric residues were fo
 und to cluster in a region of the central cavity i
 dentified previously as the substrate binding site
 . In contrast\, conserved symmetrical residues req
 uired for the transport mechanism were found at th
 e water-membrane interfaces. Three PX[DE]XX[RK] mo
 tifs form a salt bridge network on the matrix side
  of the cavity\, when the substrate binding site i
 s open to the mitochondrial intermembrane space. T
 hree [FY][DE]XX[RK] motifs are present on the cyto
 plasmic side of the cavity and they could form a s
 alt bridge network when the substrate binding site
  is accessible from the mitochondrial matrix. It i
 s proposed that the opening and closing of the car
 rier could be coupled to the disruption and format
 ion of the two salt bridge networks induced by sub
 strate binding. The interaction energies of the ne
 tworks allow members of the transporter family to 
 be classified as strict exchangers or uniporters.
LOCATION:TCM Seminar Room\, Cavendish Laboratory
CONTACT:Neil Drummond
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