EXPERIMENTAL FIGURE 14-20 GTP hydrolysis by dynamin is required for the pinching off of clathrin-coated vesicles in cell-free extracts. A preparation of nerve terminals, which undergo extensive endocytosis, was lysed by treatment with distilled water and incubated with GTP-γ-S, a nonhydrolyzable derivative of GTP. After sectioning, the preparation was treated with gold-tagged anti-dynamin antibody and viewed in the electron microscope. This image, which shows a long-necked clathrin/AP-coated bud with polymerized dynamin lining the neck, reveals that buds can form in the absence of GTP hydrolysis, but vesicles cannot pinch off. The extensive polymerization of dynamin that occurs in the presence of GTP-γ-S probably does not occur during the normal budding process.

[Republished with permission of Nature, from Takei, K. et al., “Tubular membrane invaginations coated by dynamin rings are induced by GTP-gamma S in nerve terminals,” 1995, Nature 374 (6518):186–90; permission conveyed through the Copyright Clearance Center, Inc.]