Fig. 6. Immunoblot showing the distribution of Sar1, Sec31, rBet1, apoB-48 and calnexin across a sucrose gradient. ER, cytosol and an ATP regenerating system were incubated for 30 minutes at 37°C and placed on a sucrose gradient as in Fig. 2C. The gradient was resolved and an equal volume (100 µl) of each fraction and 20 µl (60 µg protein) of the original ER and cytosol mixture (TM) were separated on SDS-PAGE. The gel was transblotted and probed with antibodies to the indicated proteins.