Chemistry Reference
In-Depth Information
Table 7.1
(Continued)
Receptor
Ligand
Technique
Receptor mobility and ligand binding properties
Reference
Binding: Non-linear Scatchard plot and sigmoid Hill plot
with n
>
1 indicatemore than one binding site with different
af
nities. The mean K
d
¼
1.6 nM.
Enzyme-linked
a
5
b
1
Integrin in
broblasts
Fibronectin (FN7-10 recom-
binant fragment) conjugated
to 1-
SPT and opti-
cal trapping
Diffusion: Low density antibody-coated beads displayed free
diffusion (monomeric unliganded integrins). Fibronectin-
or high density antibody-coated beads induced rearward
motion on lamellipodia. Cross-linking of integrins pro-
moted attachment to the cytoskeleton. Interaction of In-
tegrins with rigid sites in the extracellular matrix was
modeled by optical trapping of the beads. Restriction of
integrin movement caused localized reinforcement of the
links with the cytoskeleton.
[160]
m
m beads
a
L
b
2
integrin (LFA-1)
tagged
ICAM-1
SPT
Diffusion: Regulation of LFA-1 receptor mobility by ligand-
induced conformational changes. LFA-1 exists in at least
two distinct populations on both resting and PMA-activated
cells. Cell activation and disruption of cytoskeletal inter-
actions increased the fraction of mobile receptors indi-
cating that on resting cells a pool of receptors was con-
strained by cytoskeletal interactions. Receptors in the ac-
tive, open conformation became largely immobile and
experienced directed motion upon cell activation. ICAM-1-
ligated LFA-1 receptors were largely immobile on both
resting and activated states, due to cytoskeletal attachment.
[161]
with 1-
m beads conjugated
with antibody directed against
conformation-dependent epi-
topes in T-cells
m
