Glycoprotein processing can be studied by assessment of the sensitivity of the glycoprotein to specific hydrolytic enzymes such as endoglycosidase D. The figure below studies the time course of processing of VSV G protein after shifting the temperature of cells from 40 to 32’C. Part (a) depicts VSV G proteins resolved on SDS-PAGE; part (b) depicts the time course of change in the fraction of G protein sensitive to endoglycosidase D at either 32℃ or 40℃。 Time at 32 “C(min) 0 5 10 15 20 30 45 60 Resistant Sensitive 1.0 0.8 32 C 0.6 0.2 40 C 10 20 30 4 50 60 Time (min) The temperature shift is done in order to allow transport of glycoprotein: O From the ER to the cis-golg From the golgi to the plasma membrane. O From the plasma membrane to the late endosome. From the cis-solgi to the ER.