ß-arrestin
recruitment upon activation of WT and DRY mutants
of H1R in HEK293TN cells. (A–D) Confocal images depicting the
subcellular localization of WT H1R-mCh (A, B, upper panels) or H1R
DRY-mCh (C, D, upper panels) coexpressed together with ßarr1-mTQ2
(A, C, lower panels) or ßarr2-mTQ2 (B, D, lower panels) in HEK293TN
cells. Subcellular localization before (left) and after (right; 125
s after for the WT and at 250 s after for the DRY mutant) stimulation
with 100 μM histamine. Arrowheads point to the histamine-induced
localization of ß-arrestin at or near the plasma membrane. The
size of the images is 60 μm × 60 μm. (E) Dotplot
showing histamine-induced relocation of ß-arrestin to the plasma
membrane. WT H1R-mCh or H1R DRY-mCh was coexpressed together with
ßarr1-mTQ2 or ßarr2-mTQ2 in HEK293TN cells. The cytosolic
fraction of ß-arrestin was measured at 250 s after stimulation
with 100 μM histamine and normalized to the total ß-arrestin
content prior to stimulation; centerlines show the median. (F) Line
plot showing colocalization of ß-arrestin1 and H1R at the plasma
membrane. Fluorescence intensity of ß-arrestin1 (blue trace),
Lck (black trace), and H1R (red trace) along the line shown in the
insets. The line was drawn through the ß-arrestin puncta indicated
with the arrowhead in panel (A). (G) Line plot showing colocalization
of ß-arrestin2 and H1R at the plasma membrane. Fluorescence intensity
of ß-arrestin2 (blue trace), Lck (black trace), and H1R (red
trace) along the line shown in the insets. The line was drawn through
the ß-arrestin puncta indicated with the arrowhead in panel (B).