Fig. S2.

MS determination of the N and C termini of the shed HEMO protein. Protein coverage of the Shed Env form, purified from the supernatant of phCMV-HEMO transfected 293T cells, is shown in green characters after trypsin proteolysis and MS characterization of the resulting peptides, or with underlined characters after chymotrypsin proteolysis (SI Methods). The HEMO N and C termini are indicated by large capital letters. The signal peptide is in purple, and the transmembrane domain is in red.