||CCR5 encodes a member of the beta chemokine receptor family, which is predicted to be a seven transmembrane protein similar to G protein-coupled receptors. C-C motif chemokine receptor 5 (gene/pseudogene) is expressed by T cells and macrophages, and is known to be an important co-receptor for macrophage-tropic virus, including HIV, to enter host cells. Defective alleles of CCR5 have been associated with the HIV infection resistance. The ligands of this receptor include monocyte chemoattractant protein 2 (MCP-2， macrophage inflammatory protein 1 alph (MIP-1 alpha， macrophage inflammatory protein 1 beta (MIP-1 beta) and regulated on activation normal T expressed and secreted protein (RANTES). Expression of this gene was also detected in a promyeloblastic cell line, suggesting that C-C motif chemokine receptor 5 (gene/pseudogene) may play a role in granulocyte lineage proliferation and differentiation. CCR5 is located at the chemokine receptor gene cluster region. An allelic polymorphism in CCR5 results in both functional and non-functional alleles; the reference genome represents the functional allele. Two transcript variants encoding the same protein have been found for CCR5.