Electrophoretic
separation of
membrane proteins
There is no
good way to separate membrane proteins today,
therefore, the functions of most membrane protein are largely unknown. Today’s separations rely on affinity
chromatography, where one membrane protein is fished out of a cell
lysate by
genetically engineering an affinity label on the protein that
selectively adheres
to an antibody on a column. Our vision is that we can create a new
technique
that can separate a host of membrane proteins, avoiding the genetic
engineering
and the affinity column, saving days of labor for every protein, and
generating
an array of membrane proteins. This
would be an extremely powerful tool for research in pharmacology.
The
separation medium itself resembles
a
biological
membrane, as illustrated to the right, which is placed on an unusually
fluid
and smooth polymer cushion. The idea is that a mixture of
membrane
proteins from the cell lysate is injected,
an
electric field is applied, and separation occurs according to the
charge and
friction coefficient of each protein. We can then independently
apply an
electric field below the bilayer and the proteins will separate based
on the
charges on the intracellular side of the membrane, providing a 2D array
of membrane proteins. The proteins can then be identified by surface
mass
spectrometry and also probed for biological function with synthetic
drugs or
native ligands.
Students
working on this project learn how to grow cells
and take them apart to analyze them. Students
learn about the fundamentals of electrophoretic separations, optics and
spectroscopy, mass spectrometry, and relating their results to efforts
in
companies developing array technology and high throughput screening.
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