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SUMMARY:The transport mechanism of mitochondrial carriers based on an anal
 ysis of symmetry - Edmund Kunji (MRC Mitochondrial Biology Unit)
DTSTART:20091104T113000Z
DTEND:20091104T120000Z
UID:TALK15870@talks.cam.ac.uk
CONTACT:Neil Drummond
DESCRIPTION:The structures of mitochondrial transporters and uncoupling pr
 oteins are threefold pseudosymmetrical\, but their substrates and coupling
  ions are not. Thus\, deviations from symmetry are to be expected in the s
 ubstrate and ion-binding sites in the central aqueous cavity. By analysing
  the threefold pseudosymmetrical repeats from which their sequences are ma
 de\, conserved asymmetric residues were found to cluster in a region of th
 e central cavity identified previously as the substrate binding site. In c
 ontrast\, conserved symmetrical residues required for the transport mechan
 ism were found at the water-membrane interfaces. Three PX[DE]XX[RK] motifs
  form a salt bridge network on the matrix side of the cavity\, when the su
 bstrate binding site is open to the mitochondrial intermembrane space. Thr
 ee [FY][DE]XX[RK] motifs are present on the cytoplasmic side of the cavity
  and they could form a salt bridge network when the substrate binding site
  is accessible from the mitochondrial matrix. It is proposed that the open
 ing and closing of the carrier could be coupled to the disruption and form
 ation of the two salt bridge networks induced by substrate binding. The in
 teraction energies of the networks allow members of the transporter family
  to be classified as strict exchangers or uniporters.
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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