Chemistry Reference
In-Depth Information
Table 7.1
(Continued)
Receptor
Ligand
Technique
Receptor mobility and ligand binding properties
Reference
EGFR
in A431 carcinoma cells
EGF
labeled with Cy3 or Cy5
SMI (TIRFM)
and single
molecule
FRET
Diffusion: Single-molecule tracking revealed that in most
cases, EGFR dimerization preceded the binding of the
second EGF molecule.
[166]
Binding: EGF binding was measured on both basal and
apical surfaces. Formation of EGF
-
EGFR dimeric com-
plexes was deduced bymeasuring the intensity distribution
of the
uorescent spots at various times after the addition of
EGF-Cy3. Dimerization initiated intracellular calcium re-
sponse. Single-molecule FRET from Cy3-EGF to Cy5-EGF
proved dimer formation. After dimerization, EGFR acti-
vation was demonstrated by the use of an antibody speci
c
to the phosphorylated cytoplasmic domain.
EGFR (erbB1)
in A431 epider-
EGF
conjugated to QD
SMI
Diffusion: Binding on
lopodia and retrograde transport of
activated receptors toward the cell body were observed.
Directed transport of surface receptors proceeds via actin
[167]
mal cells
lopodia. Accessibility experiments with exposure
to an acidic medium or quenching by FRET demonstrated
that transport precedes receptor internalization.
ow in
Binding: Tracking with two-color EGF-QD ligands showed
that retrograde transport requires dimerization of erb-
B1
-
ligand complexes (2:2 dimer complex).
IgE receptor FceRI
in RBL-2H3
IgE
labeled with Alexa 488 or
Two-photon
FCS
Diffusion: Upon stimulation (IgE receptor cross-linking by
multivalent antigen) both Fc
[168]
cells
546
RI and the Src family tyrosine
kinase Lyn had a lower lateral mobility.
e
