CoroNaVirus envelope (CoV E) proteins are ~100-residue polypeptides with at least one channel-forming α-helical transmembrane (TM) domain. The extramembrane C terminal tail contains a completely conserved proline, at the center of a predicted β coil β motif. This hydrophobic motif has been reported to constitute a Golgi-targeting signal, or a second TM domain. However, no structural data for this, or other extramembrane domains in CoV E proteins, is available. Herein, we show that the E protein in the severe acute respiratory syndrome (SARS) virus has only one TM domain in micelles, whereas the predicted β coil β motif forms a short membrane-bound α helix connected by a disordered loop to the TM domain. However, complementary results suggest that this motif is potentially poised for conformational change, or in dynamic exchange with other conformations.