FIG. 2.

Epitope mapping of anti-CCR5 MAbs. A two-color staining protocol was used to assess binding of MAbs to mutant CCR5 proteins, tagged at the C terminus with the HA peptide. HeLa cells expressing CCR5 point mutants were incubated with saturating concentrations of each MAb followed by detection with a PE-labeled anti-mouse IgG. Cell surface coreceptor expression was measured by double staining of the cells with an FITC-labeled anti-HA MAb. The four grids correspond to the four extracellular domains of CCR5. The first row of every grid indicates the amino acid sequence of the corresponding CCR5 extracellular domain. Binding of anti-CCR5 MAbs to the alanine mutant of each residue is expressed as a percentage of binding to wild-type CCR5, as described in Materials and Methods.