 As illustrated in the accompanying image, the production of a coated vesicle is not instantaneous, and a considerable fraction of the maturation time is used by making "abortive" or "futile" interactions until enough interactions occur simultaneously to allow the structure to continue to develop.The last step in the formation of a transport vesicle is "pinching off" from the donor membrane.This requires energy, but even in the well studied case of CCVs, not all require dynamin.