text: The CCR family of receptors are a group of g-protein coupled receptors (GPCRs) that normally operate as chemokine receptors.  They are primarily found on immunological cells, especially T-cells. CCR receptors are also expressed on neuronal cells, such as dendrites and microglia. Perhaps the most famous and well-studied of the CCR family is CCR5 (and its near-homologue CXCR4) which acts as the primary co-receptor for HIV viral infection. The HIV envelope glycoprotein GP120 binds to CD4 as its primary receptor, CCR5 then forms a complex with CD4 and HIV, allowing viral entry into the cell. CCR5 is not the only member of the CCR family that allows for HIV infection. Due to the commonality of structures found throughout the family, CCR2b, CCR3, and CCR8 can be utilized by some HIV strains as co-receptors to facilitate infection. CXCR4 is very similar to CCR5 in structure. While only some HIV strains can utilize CCR2b, CCR3 and CCR8, all HIV strains can infect through CCR5 and CXCR4.
  CCR5 is known to have an affinity for macrophage inflammatory protein (MIP) and is thought to play a role in inflammatory immunological responses. The primary role of this receptor is less understood than its role in HIV infection, as inflammation responses remain a poorly understood facet of the immune system. CCR5's affinity for MIP makes it of great interest for practical applications such as tissue engineering, where attempts are being made to control host inflammatory and immunological responses at a cellular signalling level. The affinity for MIP has been utilized in-vitro to prevent HIV infection through ligand competition; however, these entry-inhibitors have failed in-vivo due to the highly adaptive nature of HIV and toxicity concerns.