Figure 1. β-Actin surrounds synaptic vesicle clusters.

A, an example of anti-β-actin staining in control (upper) and stimulated (lower) nerve terminals. The staining forms regular rings along the length of the control nerve terminal. The right panel shows a nerve terminal stimulated for 5 min at 30 Hz immediately prior to fixation; here the actin staining is less regular, as though it has been partially disrupted. Scale bar = 2 μm. B, two examples of nerve terminals loaded with FM4-64 (left-hand column), then fixed and stained for β-actin (middle column). The images are merged in the images in the right-hand column, which show little overlap. C, staining of postsynaptic acetylcholine receptors with rhodamine-conjugated α-bungarotoxin (left-hand panel) and of β-actin (middle panel). The right-hand panel is an overlay image, showing that the actin surrounds areas that lie directly above the postsynaptic folds. Scale bar = 1 μm for B and C.