Biology Reference
In-Depth Information
FIGURE 7.3
Functional evidence of 5-HT
4
R dimerization at the cell surface. Myc-5-HT
4
RWT (in red, A, B,
and C), RhoTag-5-HT
4
R-D
100
A (in green, D, E, F), or both (G-O) were transiently expressed
in HEK-293 cells and visualized by immunofluorescence confocal microscopy. Cells are
fixed in basal conditions (A, D, G, J, and M) or after a 30 min exposure with 10
m
M of either
5-HT (B, E, H, K, and N) or BIMU8 (C, F, I, L, and O).
bind to D
100
A, induced an internalization of this mutant receptor, when the D
100
A
mutant was coexpressed with WT receptor (
Fig. 7.3
K and N). Indeed, 5-HT induced
the internalization of WT/WT dimers (
Fig. 7.3
H and N, red dots) and of WT/D
100
A
dimers (
Fig. 7.3
H, K, and N, yellow dots), whereas D
100
A/D
100
A dimers remained at
the cell surface (
Fig. 7.3
K and N, green dots). All types of complexes internalized
after a 30 min exposure with BIMU8 (
Fig. 7.3
I, L, and O). The simplest explanation
of these results implicates the existence of a WT/D
100
A dimer. When the WT mono-
mer of the WT/D
100
A dimer was occupied by 5-HT, both WT and D
100
A protomers
were internalized.