FIG 7.

Model for regulation of the participation of palmitoylated TF in alphavirus assembly. TF is targeted to the site of budding via a 2-step regulatory mechanism. First, the C-terminal domain regulates the palmitoylation state of TF. The conserved Cys residues in the N-terminal shared cytoplasmic region are palmitoylated. Second, palmitoylation on TF targets the protein to the plasma membrane, where it participates in the assembly and budding of WT particles. When the C-terminal domain lacks the Cys residues, TF is still targeted to the plasma membrane by N-terminal palmitoylation, as in 4C. When palmitoylation is missing as in 5C and 9C, TF is not targeted to the plasma membrane efficiently.