<prompt> Which of the following sequence is directed in a retrograde manner to EPR in COP-1 vesicles?KDELKDALDALKKDUL  <response>: KDEL sequence lysine - aspaate - glutamate - leucine at carboxy terminal first travel to GA in COP-2 vesicles, interact with their specific receptor protein. then they return in a COP-1 vesicle to EPR, get dissociate from their receptor are retrieved. Reference: Harper; 30th edition 