Figure 5.

Reconstitution of agonist-induced β₂-AR sequestration by β-arrestin 1 or 2 in βarr1/2-KO MEFs. (A and B) βarr1/2-KO cells (line 10) were infected with various multiplicities of infection of βarr1-Ad (A) or βarr2-Ad (B) and sufficient β₂-AR Ad to express β₂-AR at approximately 200 fmol/mg. The level of β-arrestin expression in each infection was determined by Western blotting of cell lysates (Upper) followed by comparison to a standard curve of β-arrestin1-Flag and β-arrestin2-Flag proteins. Isoproterenol-induced β₂-AR sequestration for each infection was then determined (Lower). A and B show a representative experiment (n = 5). For comparison, the same protein concentration from WT cell lysates was immunoblotted and its isoproterenol-induced sequestration is represented as a dashed line in the bar graph. (C) Pooled data from all experiments showing effect of β-arrestin expression on the ability of βarr1/2-KO cells to sequester the β₂-AR.