A combination of cell-free biochemical and morphological studies has revealed that a coated bud-coated vesicle transport system shuttles newly synthesized proteins through the successive processing compartments of the Golgi apparatus. These Golgi-coated vesicles operate in a manner formally analogous to the clathrin-coated, pit-coated vesicle system responsible for receptor-mediated endocytosis; however Golgi-coated vesicles do not contain clathrin.