Sort the following events to reflect the order in which they occur during the formation of vesicles from the ER destined for the Golgi apparatus. Your answer would be a four-letter string composed of letters A to D only, e.g. DACB.
(A) Sar1 GTP hydrolysis
(B) Sar1 GTP binding
(C) Sar1-Sec23 binding
(D) Sar1 membrane association