Chemokine receptors are seven-transmembrane domain G-protein coupled receptors that mediate the biological activities of chemokines. Most of these receptors exhibit promiscuous binding properties whereby several different chemokines signal through the same receptor. They are named according to the chemokine subfamily they bind. There are currently eleven CC-specific receptors designated CCR1 to CCR11.
HCR (Human Chemokine Receptor), also known as CRAM, CKRX, and CCRL2, is a G protein-linked seven transmembrane domain spanning chemokine receptor that exists in two isoforms CRAM-A and CRAM-B. The two isoforms differ at the N-terminus with CRAM-A having an additional 12 amino acids. Cells reported to express HCR/CRAM include peripheral blood cells, monocytes, neutrophils, and T cells.