Areas of use

OEP21 - A sweeping examle of use


OEP21, a pore forming membrane protein from the outer membrane of chloroplasts, was investigated using the Ionovation Compact. Proteoliposomes containing expressed PEP21 as well as membrane vesicles from the outer chloroplastic membrane were fused with the bilayer. A set of voltage ramps from -50mV applied to a bilayer containing one single copy of OEP21 is shown:

 

a)

Asymmetrical salt concentration of 2 M NaCl on the CIS side and 250 mM NaCl on the TRANS side.

b)

Addition of 1mM ATP to the low salt (TRANS) side. A shift in the reversal potential and a voltage dependent current block is obvious.

c)

Changing the salt gradient vice versa by perfusion of the compartments reveals a mirrored situation to a) showing that the block of ATP is reversible.

d)

Addition of 1mM ATP to the new low salt (CIS) side gives no changes in reversal potential current.

This shows that ATP has a high affinity to OEP21 on only one side of the membrane, revealing the asymmetrical structure of this protein in a membrane, that so far was thougt to be an unspecific diffusion barrier for solutes < 10 kDa.

© copyright by Ionovation GmbH, Osnabrück, 2004-2008

 

Ionovation Technology can be used in all areas where electrophysiological measurements are done today. In the area of ion channels and membrane transporters today this includes

 

Target identification and validation
Pharmacology Screening
Drug safety / early ADME-Tox

 

Furthermore the new possibilities offered with advanced bilayer techniques open new insights in novel areas of reseach. The combined observation of e.g. binding events and electrical currents provides the chance to elucidate

  • the general influence of specific effectors binding to biomembranes (such as prions and synucleins).
  • that certain biomolecules of not fully understood function alter membrane conductivity by binding to them.

 


Applications (pdf):

 

Channels and Transporters measured using a Ionotec setup:

  • Sec61p complex
  • OEP21 anion selective chloroplast solute channel
  • plastid envelope preprotein conducting channel
  • Toc75 chloroplast protein import channel
  • Tim22 mitochondrial protein insertion complex
  • Tim23 mitochondrial preprotein translocase
  • Ca(2+)- and voltage-modulated flagellar ion channel
  • OEP16 outer chloroplast envelope protein
  • K+-channel from Streptomyces lividans
  • and many more ...

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