Biomedical Engineering Reference
In-Depth Information
biochemical functions within distinct organelles, in localizing metabolic processes,
and in communication between internal compartments and the extracellular envi-
ronment. Dysfunction in membrane proteins and associated compartmentalization
processes are common causes of human disease. The lipid bilayer of cell membranes
presents a unique two-dimensional hydrophobic environment for membrane proteins.
Specialized in both structure and function, the study of membrane proteins provides
a unique array of technical challenges and research opportunities. Diseases related
to membrane proteins result from changes in the function of the membrane protein
caused by structural damage and mutations. Underlying genetic changes may cause
either: (i) retention of the protein in an intracellular location, instead of reaching the
plasma membrane, or (ii) change of function of the protein. The so-called MTC tech-
nique enables differentiation of these possibilities. Live-cell confocal microscopy,
in combination with fluorescently tagged proteins and ion-sensitive dyes, allows
high fidelity spatial and temporal measurements to reveal dysfunctional molecular
trafficking, as well as to measure disturbances in the ionic milieu associated with
alterations in the function of many membrane proteins. Many ion transport proteins
operate by moving charged ions/molecules across the cell membrane, and this can
be measured in “real time” on the scale of milliseconds using state-of-the-art patch-
clamp technologies. Combining these electrophysiological recordings with confocal
fluorescent measurements makes it possible to diagnose the nature of the membrane
transport defect in a single step with unparalleled precision.
Gene Transduction Core (GTC)
A common approach to understanding the basis
for diseases caused by membrane proteins is to measure the function of recombi-
nant mutant proteins. These studies are typically performed in immortalized tissue
culture cells. However, these immortalized cells often do not behave as wild-type
primary cells, and do not provide a normal background, so results obtained from
measurements performed on these cells may be inaccurate. Recently developed viral
transduction methodologies have begun to allow mutant genes to be introduced in
vivo and in vitro into cells from many tissues. These primary tissue culture cells,
very recently explanted from their host, behave in a more realistic manner, but these
cells are resistant to the introduction of genes. The GTC enables new methodologies
of viral gene transduction to induce expression of individual genes in primary tissue
preparations and cell cultures.
Protein Modeling and Dynamics Core (PMDC)
Membrane proteins are cen-
tral to cellular function and also represent important targets for drug discovery.
Indeed, G-protein coupled receptors (GPCR) are not only membrane proteins,
but also constitute a major target of drug therapies in use today. Directed design
of drugs requires information on the structure of the target (membrane protein).
The PMDC provides a two-pronged approach to set the stage for targeted drug
design involving: (i) computer modeling of protein membrane structures, and (ii)
experimental determination of three-dimensional structures of membrane proteins.
A cluster of computers with appropriate software packages enables: (a) modeling of
the dynamics (movements) of membrane proteins, (b) virtual docking of molecules
(potential drugs) onto the surfaces of membrane proteins to identify and rank potential
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