Fig. 3. Sequence alignment of VP40 from Ebola virus (strain Zaire, DDBJ/EMBL/GenBank accession No. AF086833) and from Marburg virus (strain Popp, DDBJ/EMBL/GenBank accession No. Z29337). Identical residues are shown in red letters and conservative substitutions in blue. The sequence present in the structure is shown schematically with the assignment of secondary structure elements (based on the structure of Ebola virus VP40). The black arrows at positions 31 and 326 indicate the first and last residues present in the construct used for crystallization. The yellow arrow at position 212 indicates the position of the trypsin cleavage site that induces hexamerization of VP40 in solution in vitro (Ruigrok et al., 2000b). The numbering is according to the Ebola virus VP40 sequence.