2D protein diffusion in membranes
A graduation/internship position is available at the Biomedical Engineering and Physics department
of the Academic Medical Center (AMC). In our group, new treatment and diagnostic procedures
based on innovative physical techniques are developed. Research is performed by a multidisciplinary
team that includes physicists, engineers, mathematicians, medical doctors, biologists, and chemists.
Background
Membrane proteins diffuse generally only in lateral direction. Movement in one direction is limited
by the bilipid membrane. This 2D diffusion distributes the proteins equally over the membrane, if we
neglect movement restriction by for example binding to other (fixed) molecules (figure 1A).
Application of external fixation forces on proteins, for example fixation to a surface coated with
complementary antibodies, affects this distribution. When a membrane is closely positioned to
these antibodies, the complementary membrane protein will bind to an antibody. This binding will
occur eventually with all proteins closely positioned to the antibodies, causing local depletion of free
moving proteins. We hypothesize that this results in a disturbance in the diffusion equilibrium.
Consequently, proteins are redistributed over the membrane (figure 1B) and basically brings new
proteins in the region close to the antibodies. Assuming there are sufficient available antibodies, this
process will repeat continuously. Eventually, we hypothesize that this process will cause depletion of
the membrane protein on other sites on the membrane. (Nearly) all proteins will bind to the
antibodies (figure 1C).
Recent developments
In recent experiments, we tested the distribution of the protein membrane EpCAM on human breast
cancer cells after depositing them on surface coated with antibodies. Cells will adhere to the surface
and antigens will be captured by the surface antibodies. With secondary fluorescent staining we
noticed depletion of EpCAM on the opposite side of the cells, indicating that antigen binding to
antibodies influences antigen distribution on in the membrane. We want to further develop this
analysis method for antigen redistribution analysis.
(A)
(B)
(C)
Figure 1 (A) A cell contains membrane proteins which are usually equally distributed over the membrane. (B)
After antigen capture with an antibody (green region), we expect that the remaining proteins redistribute
towards the capture region. (C) This causes new binding events, which eventually results in capture of nearly all
membrane proteins with the antibodies.
Research description
In this project you will be working on a brand new detection method to analyze diffusion of
membrane proteins in 2D. You will use cells and extracellular vesicles to examine redistribution by
e.g. fixation steps to block membrane antigen movement. Analysis will be done by different high-end
techniques such as Surface Plasmon Resonance imaging, EV-dedicated Flow Cytometry, fluorescence
ELISA and different microscopy techniques.
Requirements
We are looking for a master student with a background in biomedical sciences, biomedical
engineering or physics. Laboratory experience is preferred and basic knowledge about biochemistry
is advisable.
Learning outcome
The student will gain knowledge in the field of immunochemistry and develop laboratory skills and
data analysis skills. Being part of an interdisciplinary and internationally leading research group the
student will acquire competences including: (1) collaboration, (2) scientific writing, and (3)
presentations.
Contact
Name: Elmar Gool
Email address: [email protected]
Website: http://www.amc.nl/bmep
Phone: +31 (0)20 56 64386