Figure 9.

Disrupting the STAM-1/arrestin-2 interaction inhibits HRS ubiquitination but does not effect on CXCR4 and STAM-1 ubiquitination. (A) HEK293 cells stably expressing HA-CXCR4 were transfected with FLAG-ubiquitin and STAM-1-GAT domain or pCMV. (B) HeLa cells were transfected with HA-ubiquitin, T7-STAM-1, and STAM-1-GAT or pCMV. (C) Cells were transfected as in A, except T7-HRS was also transfected. Cells were serum starved and treated with 30 nM CXCL12 for 30–60 min, followed by immunoprecipitation and immunoblotting to detect incorporated ubiquitin as described in Materials and Methods. Shown are representative blots from six (A) or three (B and C) independent experiments.