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

To test the role of the cytoplasmic tail of Gml in oligomer formation, we inserted a stop codon after the first residue (Arg) beyond the transmembrane domain (tGml). The corresponding tailless VSV G (TMR; Doms et al., 1988) trimerizes with normal kinetics but is transported slowly from the ER to the plasma membrane. When tGml was localized by Figure 6 . amlG forms an SDS-resistant oligomer. HeLa cells transfected with amlG or am were metabolically labeled for 5 rain, and then solubilized either immediately or after a 60-min chase and immunoprecipitated with anti-hCG antibody. Samples were analyzed by SDS-PAGE on 15 % gels. Note the time-dependent accumulation of an SDS-resistant species at the interface between the separating and stacking gels (arrowhead). The increased mobility of amlG and am after 60 min of chase is due to carbohydrate trimming.