Indicate whether each of the following descriptions better applies to COPI- (1), COPII- (2), or clathrin- (3) coated vesicles. Your answer would be a four-digit number composed of digits 1 to 3 only, e.g. 1322.
( ) They mediate transport from the ER to the cis Golgi network.
( ) Their coat protein forms a three-legged structure called a triskelion.
( ) They are pinched off from their donor compartment by a dynamin collar.
( ) They are involved in retrograde transport in the Golgi apparatus.