Coated vesicles are transport vesicles that bud off from specialized regions of the cell membrane. Specific coat proteins cover their cytosolic surface. Based on the type of protein coats, these vesicles can be of three types: coat protein or COP-coated vesicles, COPI and COPII, and clathrin-coated vesicles. COPI vesicles transport molecules between different parts of the Golgi body and from the Golgi back to the rough ER. COPII vesicles are formed in the ER membranes and mediate transport from ER to the Golgi. COPI and COPII vesicles are composed of similar coat protein complexes called coatomers. These bend the membrane to form a bud that is released from the donor membrane as a vesicle.