Human CCR3 Synthetic Peptide. CCR3 (C-C chemokine receptor type 3) binds to eotaxin, eotaxin-3, MCP-3, MCP-4, RANTES, and MIP-1 delta. CCR3 trasnduces a signal by increasing the intracellular calcium ions level. It also serves as an alternative co-receptor with CD4 for HIV-1 infection. Other chemokines play important roles in inflammation and are critical for the recruitment of effector immune cells to sites of infection. Chemokines activate leukocytes by binding to G protein coupled receptors. The ever-growing chemokine receptor subtypes can be divided into 2 major groups, CXCR and CCR, based on the 2 major classes of chemokines.