Dynamin, a GTPase involved in endocytosis, is specifically required for the formation of coated vesicles. Mutant dynamin, defective in GTP binding and hydrolysis, blocks the constriction of coated pits and subsequent budding of vesicles, inhibiting endocytosis via transferrin (Tfn) and EGF receptors. Despite this, coated pit assembly, invagination, and receptor recruitment remain unaffected. Other vesicular transport pathways, including Tfn receptor recycling and biosynthesis, are not impacted. Dynamin is localized to clathrin-coated pits on the plasma membrane and is associated with isolated coated vesicles, suggesting a role in vesicle budding. Overexpression of mutant dynamin leads to the accumulation of long tubules connected to the plasma membrane, similar to the Drosophila shibire mutant. Dynamin's GTPase activity is essential for coated pit constriction and vesicle budding. The study confirms that dynamin is specifically targeted to coated pits at the plasma membrane, where it is required for coated pit constriction and vesicle budding. The results indicate that dynamin's GTP binding and hydrolysis activities are critical for endocytic coated vesicle formation. The findings support the conclusion that dynamin is specifically required for endocytic coated vesicle formation, and its GTP binding and hydrolysis activities are necessary for coated pit constriction and subsequent vesicle budding.Dynamin, a GTPase involved in endocytosis, is specifically required for the formation of coated vesicles. Mutant dynamin, defective in GTP binding and hydrolysis, blocks the constriction of coated pits and subsequent budding of vesicles, inhibiting endocytosis via transferrin (Tfn) and EGF receptors. Despite this, coated pit assembly, invagination, and receptor recruitment remain unaffected. Other vesicular transport pathways, including Tfn receptor recycling and biosynthesis, are not impacted. Dynamin is localized to clathrin-coated pits on the plasma membrane and is associated with isolated coated vesicles, suggesting a role in vesicle budding. Overexpression of mutant dynamin leads to the accumulation of long tubules connected to the plasma membrane, similar to the Drosophila shibire mutant. Dynamin's GTPase activity is essential for coated pit constriction and vesicle budding. The study confirms that dynamin is specifically targeted to coated pits at the plasma membrane, where it is required for coated pit constriction and vesicle budding. The results indicate that dynamin's GTP binding and hydrolysis activities are critical for endocytic coated vesicle formation. The findings support the conclusion that dynamin is specifically required for endocytic coated vesicle formation, and its GTP binding and hydrolysis activities are necessary for coated pit constriction and subsequent vesicle budding.