Figure 5.

Crosslinking of DAD1 to OST subunits. The purified OST was incubated with 75 μM DSP or 75 μM DTSSP (A), and PK-RM were incubated with 300 μM DSP or 300 μM DTSSP (B) as described. The OST subunits and the crosslinked products (CL-1–CL-5) were detected on protein immunoblots using antibodies specific for DAD1, ribophorins I (R I) and II (R II), and the lumenal domain of OST48. After primary and secondary antibodies were stripped from blots by exposure to acid pH, the blots were reprobed with antibodies to the other subunit to demonstrate the precise comigration of a given crosslinked product. The asterisk in A designates a proteolytic fragment of OST48 that was detected in the purified OST complex.