Oligomerization of a membrane protein correlates with its retention in the Golgi complex

The time course of Gml oligomerization was determined. HeLa cells expressing Gml were metabolically labeled for 5 min, chased for the indicated times, solubilized, and immunoprecipitated with anti-VSV G antibody (Fig. 3) . Oligo- Figure 2 . SDS-resistant oligomers are not subject to cell surface biotinylation. Ceils were metabolically radiolabeled for 15 min, and then chased for 60 rain. Cell surface-specific biotinylatiun was performed at 4"C using sulfo-NHS-biotin, and the cells were solubilized and immunopreeipitated with anti-VSV antibody. The bound protein was eluted from S. aureus pellets and divided in half. One aliquot was solubilized in sample buffer (T), and the remainder was incubated with streptavidin-coupled agarose beads. The supematant (IS], unbound material) was collected and TCA precipitated, and the streptavidin beads (P) were washed and solubilized before SDS-gel electrophoresis. merization was not detected immediately after synthesis of Gml, but occurred gradually with a lag of ~10 min.