A Golgi retention signal in a membrane-spanning domain of coronavirus E1 protein

Our results suggested that ml was indeed a retention signal when it was the only membrane-spanning domain in the protein. To confirm that the chimeric VSV G protein Gml was retained specifically by the ml sequence, we introduced the two mutations found to release retention of Om2,3 most efficiently (QI37 and mlins) . Both Gm1QI and Gmlins were transported to the plasma membrane, as shown by indirect immunofluorescence (Fig. 9 ). Both of these proteins were transported efficiently, but less rapidly than wild-type G protein, as shown by the halftimes of oligosaccharide processing (Fig. 10 ). Gm1QI and Gmlins were processed with half times of 25 and 35 min, respectively, as compared to 18 min for wild-type G protein. When assayed for oligomerization on sucrose gradients, both Gm1QI and Gmlins were found to form normal trimers (not shown) . These results suggest that Gml is retained specifically via the ml sequence and not nonspecifically because of misfolding .