Figure 4.
Export from reconstituted microsomes. (a) Microsomes reconstituted with CTA1 and lumenal ER proteins (see Materials and Methods) were resuspended in export buffer with or without ATP and used for an export reaction as described in Fig. 3 a. CTA1 was detected by immunoblot using an anti–cholera toxin antiserum. The export rates per hour were <1% in the absence of ATP and 9% in the presence of ATP, respectively. 10 ng of the CTA1 used for the reconstitution was loaded as a standard (st). (b) Reconstituted microsomes were treated with 100 μg/ml trypsin in the absence or presence of TX-100. CTA1 was detected by immunoblot.