BUNV M RNA segment and mutagenesis of the glycoprotein precursor. The layout of the BUNV M segment-encoded gene product is shown at the top, with positions of amino acid residues marking protein boundaries (Gn, NSm, and Gc) indicated. ss, signal peptide; TMD, transmembrane domain. Below are shown alignments of the CT domains of Gn and Gc proteins from eight orthobunyaviruses and sequences of the BUNV mutants containing sequential substitutions with strings of five alanine residues. Abbreviations: CEV, California encephalitis virus (GenBank database accession number AAD53039); LACV, La Crosse virus (AAB62804); INKV, Inkoo virus (AAB93841); SRV, South River virus (AAD53044); JCV, Jamestown Canyon virus (AAB93842); MAGV, Maguari virus (AAQ23639); NGAV, Ngari virus (AAT01931); BUNV, Bunyamwera virus (NP_047212).