|
|
|
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
|
Fig. 6. Wingless accelerates Frizzled2 internalization. (A,B) Imaginal disc of the
genotype hs-FLAG-Frizzled2 fixed 1.5 hours after a pulse of uniform expression
of tagged Frizzled2 (A) and Wingless (B). Note the relative increase in
vesicular Frizzled2 around the area of Wingless expression. As many of these
vesicles also contain Wingless (insets), it appears that Wingless stimulates
Frizzled2 internalization. (C,D) Imaginal discs of the same genotype
(hs-FLAG-Frizzled2) fixed 50 minutes (C) or 3 hours (D) after heat-shock and
stained with anti-FLAG. Fifty minutes after the pulse, Frizzled2 is found
throughout the disc, predominantly outlining cell membranes, whereas after 3
hours, the level of Frizzled2 appears preferentially reduced in the area
surrounding the source of Wingless (the central region of the pouch)
suggesting, possibly, increased degradation. (E) Imaginal disc 1 hour after
uniform induction of Patched expression. The protein (as detected with an
anti-Patched antibody) is seen uniformly throughout the disc. (F) Three hours
after induction, the Patched protein is preferentially reduced in the
posterior compartment, where its ligand, Hedgehog is expressed. Staining along
the anteroposterior boundary could originate from endogenous expression as an
anti-Patched antibody was used. However, deeper into the anterior and
posterior compartments, Patched is not normally expressed and protein turnover
can be compared in these two domains. (G,H) Division of labour between
Frizzled2 and Arrow. (G) Frizzled2 provides most of the capturing activity,
while Arrow brings a degradation signal. Both receptors provide an
internalization signal. (H) When Frizzled2 is in relative excess at the cell
surface, Wingless is captured and put on hold until Arrow becomes available to
signal and trigger degradation.
|
