Fig. 6. Sequential interaction of SIQ/P with BiP and calnexin. COS-1 cells were transfected with pSG8-Ala1 and pSG8-Ala31. (A) Forty-eight hours post-transfection the cells were biosynthetically labelled at 37°C for 6 hours followed by cell lysis and immunoprecipitation of SI. The cell lysates were immunoprecipitated with anti-BiP or anti-calnexin and subsequently with mAb anti-SI. (B) Transiently transfected COS-1 cells were labelled for 30 minutes followed by different chase intervals at 20°C. The cell lysates were immunoprecipitated sequentially with mAb anti-SI and anti-BiP or anti-calnexin. The samples were analysed with SDS-PAGE and phosphoimaging.