SARS-CoV S palmitoylation can occur in a pre-medial Golgi compartment and is a stable modification. (A) At 24 h post-transfection, HEK293T cells expressing SARS-CoV S were labeled with 35S-methionine/cysteine or 3H-palmitic acid for 30 min. After lysis, S protein was immunoprecipitated, denatured, digested with endo H, separated by SDS–PAGE and imaged by fluorography. (B) At 24 h post-transfection, HEK293T cells expressing SARS-CoV S were labeled with 35S-methionine/cysteine or 3H-palmitic acid for 30 min and chased for 0, 40, 80 or 120 min. After lysis, S protein was immunoprecipitated, separated by SDS–PAGE and analyzed by fluorography for 24 h (35S) or for 1 wk (3H).