FIG. 1.

Overview of mutant M proteins. In the middle is a schematic representation of the structure of the M protein, with the three transmembrane (TM) domains indicated. Amino acid sequences of the amino-terminal and carboxy-terminal domains, and of the mutants with mutations in these domains, are shown above and below the diagram, respectively. Dashes represent unchanged residues, gaps represent deletions. The domain deleted in mutant ΔC (residues E₁₂₁ through D₁₉₅) is indicated by a horizontal line. The abilities of the different M proteins to support VLP assembly is indicated at the right. The ratio of the amount of M present in the culture medium to that in cells was taken as a measure for VLP assembly by using WT M as a reference. The semiquantitative scores ++, +, +/−, and − indicate efficient, moderately efficient, inefficient, and nonexistent VLP synthesis, respectively.