FIGURE 1. Ability of the mutant CCR2V64I receptor to form heterodimers with the CXCR4 receptor.

a, HEK-293 cells, which constitutively express CXCR4, were transfected with the expression vector for CCR2V64I and stained¹⁰ with a monoclonal antibody specific for CCR2 and CXCR4, using isotype-matched antibody as a control. b, CCR2V64I-transfected HEK-293 cells were stimulated with chemokines (10 nM, 5 min at 37 °C) and, where indicated, crosslinked with 1 mM DSS. Cell lysates were immunoprecipitated with anti-CCR2 antibody, electrophoresed and transferred to nitrocellulose membranes. The western blot was analysed with anti-CXCR4 antibody; as a positive control, lysates from the same cells were immunoprecipitated with anti-CXCR4 antibody (left). The membrane was stripped and reblotted with anti-CCR2 antibody as a protein loading control (right). Arrows indicate the monomer and dimer.