Tethered Membrane Products

Tethered membranes are lipid bilayers that have been chemically attached to a thin gold film that acts as an electrode. Between the membrane and the gold film as part of the covalent structure of the membrane lipids is a hydrophilic layer (an ion reservoir) that mimics the interior of a cell allowing the sensitive detection of changes in the electrical properties of the membrane as a result of insertion of channels and the exposure of those channels to chemicals that effect the channel condution.

SDxResearch provides ready to use bilayers with a variety of lipid compositions or tethered lipids for use with lipids of choice.

Ion channels peptides or proteins can be inserted into the bilayer from aqueous or ethanolic solution, from proteoliposomes or with mild detergents depending on the nature of the peptide or protein under evaluation.

The efficiency of insertion of proteins into the tethered membranes depends on the molecular size of the protein and the spacing of the tethered lipid bilayer.

SDx provides membranes with tethering ratios from 1% to 90% to allow the insertion efficiency and the stability to be optimized for particular proteins being studied.

Applications

Ion channels can be readily inserted into tethered lipid membranes with various lipid constructs.

A. The conductance of Tethered Membranes (TM) containing Voltaged Dependent Anion Channel (VDAC) has been studied using SDxResearch tethered membrane slides and impedance reader.  Figure 1 shows the conductivity changes that occur when the tethered membrane is exposed to liposomes containing VDAC and the effect on conductivity that results from incubation with various ionic species and when blocked with DIDS (unpublished data from Professor Don Martin, Université Joseph Fourier, Grenoble, France).

Figure 1

B. Chloride Intracellular Channels (CLIC) insert directly from aqueous solution.  Insertion kinetics of CLIC have been studied (Figure 2) using CLIC proteins sourced from different species including human and drosophila (unpublished data from Dr Stella Valenzuela, University of Technology, Sydney, Australia)

Figure 2

  Other systems studied include:    

• Maxi-K potassium channels
• Mechanosensitive channel (MscL).

SDx will work with you to develop an assay for your Channel or membrane of interest.