FIG. 2.

CD81 sequence and structure. (A) Comparison of human, mouse, and rat CD81 LEL sequences. Residues differing between human and mouse CD81 proteins are shaded in gray. Most of these residues are also different in rat CD81 and are therefore not indicated. The two additional residues that differ in rat CD81 are shaded in black. (B) Predicted two-dimensional structure of CD81, including the two extracellular loops, four transmembrane helices, and the intracellular loop along with the intracellular N-terminal and C-terminal tails. LEL residues that were mutagenized in this study are shown using the same color code as that in panel A. Polar transmembrane residues and intracellular cysteines that were mutagenized are indicated in white circles and squares, respectively.