Alignment and helical wheel analysis of predicted transmembrane domains for representative coronavirus E proteins. (A) Alignment of transmembrane domains for E proteins for viruses representative of the three subgroups. Transmembrane domains were predicted using TMHMM 2.0 (http://www.cbs.dtu.dk). Sequences for porcine transmissible gastroenteritis coronavirus (TGEV) (accession no. AY335549.1), feline infectious bronchitis virus (FIPV) (AY994055.1), human coronavirus 229E (AF304460.1)), MHV A59 (NC001846.1), bovine coronavirus (BCV) (U00735.2), human coronavirus OC43 (AY903460.1), SARS-CoV (AY278741.1), IBV (DQ001338.1), and turkey coronavirus (TCV) (AJ310640.1) were obtained from GenBank. Hydrophilic polar residues are in boldface. (B) Helical wheel plots for E proteins from the representative coronaviruses are shown as described for Fig. 6.