FIGURE 2.

Activity of synthetic Z8 peptide and recombinant agrin G3 domains. AChR clustering was not detected in C2C12 myotubes treated with (A) no agrin protein, (B) 1 μg/ml AgG3z0, (C) 1 μg/ml or (D) 100 μg/ml synthetic z8 peptide. Incubation with 1 μg/ml AgG3z8 induced patch-like AChR cluster formation (E), which persisted in the presence of 100 μg/ml synthetic z8 peptide (F). The AChRs on muscle cell surface were labeled with rhodamine-conjugated α-bungarotoxin and examined under a fluorescent microscope. G, fluorescent labeled receptor clusters in each visual field photographed and measured using the ImageJ software. The data represent the mean ± S.E. (error bars) of results from four independent experiments.