Biomedical Engineering Reference
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Figure 2.2
Integrin subunits embedded lipid membrane with connection to ECM.
highly variable in nature with a particular composition being associated with a
specific function of the tissue involved. The chemistry exhibited by the ECM
macromolecules is connected to cellular proliferation, structural integrity and
adhesive properties. 7 Examples of the structural proteins are collagen and
elastin and for those involved in adherence, fibronectin and laminin. The ECM
in connective tissue has incorporated cells relatively sparsely spaced, whereas in
the epithelium they are in close proximity with each other. The interaction of
various cells with the ECM is mediated by membrane-bound proteinaceous
entities known as integrins. These proteins effectively connect together the
cytoskeleton with proteins in the ECM such as laminin, fibronectin and
collagen. They are present in the lipid membrane in the form of a dimer and
take a variety of forms capable of attaching to ECM proteins (Figure 2.2). 8 The
interaction between integrin and ECM components is complex and involves
conformational changes in the former often described in terms of focal
adhesions. This binding event is associated with a conserved RGD sequence in
the ECM proteins. 9 As one example of the processes involved we mention the
chemistry of fibronectin, which is a fibril-forming glycoprotein with a dimeric
structure composed of 230-270 kD monomers. The protein contains domains
that bind to a number of moieties such as collagen, ECM proteins and the cell
membrane. The cell binding region of the protein possesses the RGD sequence
which attaches by hydrogen bonding to glycine residues in integrins. 10
The ECM chemistry is highly relevant to protocols for the modification of
surfaces. Not surprisingly, in order to promote solid-substrate binding of
various cells, the interface has first been treated with ECM proteins on a so-
called inert background. Such efforts are discussed in more detail later is this
chapter.
n 3 .
2.4 The Neuron: A PreĀ“ cis
Contemporary neuroscience is a highly interdisciplinary field incorporating
biology, chemistry physics, engineering and computer science among many
 
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