Figure 1.

Artistic rendition of the structures that form a fusion pore according to the scaffold hypothesis. The figure shows a depression of the plasma membrane that is caused by a scaffold of proteins. At the tip of the depression, the highly curved lipid membrane is thought to fuse, spontaneously, with the granule membrane, creating a lipid-lined fusion pore. It is possible that the AFM images of fusion pores presented by Schneider et al. (6) correspond to the structures associated with the mouth of the depression shown in the figure. This figure was modified from Monck and Fernandez (9).