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

chor . Russo et al . (40) have found that the amino terminus of 01,4 galactosyl transferase (including the cytoplasmic tail and membrane-spanning domain) is sufficient to target a marker protein, pyruvate kinase, to Golgi membranes (40; Russo, R . N., N. L. Shaper, and J. H. Shaper, manuscript in preparation) . In addition, no lumenal, nonmembranebound Golgi proteins have yet been identified . All of these observations are consistent with the idea that sequences bu- Figure 10 . Rate of transport of Gm1QI and Gmlins through the Golgi. Transfected COS cells expressing G, Gml, Gm1QI, or Gmlins were labeled for 10 min with ['SS]cysteine, and chased in unlabeled cysteine for the times shown. Lysates were immunoprecipitated, and left untreated (-) or digested with endo H (+). The oligosaccharides on both Gm1QI and Gmlins are processed to an endo H-resistant form efficiently, but somewhat more slowly than those on the wild-type G protein.