chemokines

Small secreted proteins that stimulate chemotaxis of leucocytes. Chemokines can be subdivided into classes on the basis of conserved cysteine residues. The a -chemokines (IL-8, NAP-2, Gro- a, Gro- g, ENA-78 and GCP-2) have conserved C-X-C motif and are mainly chemotactic for neutrophils; the b -chemokines (MCP-1-5, MIP-1 a, MIP-1 b, eotaxin, RANTES) have adjacent cysteines (C-C) and attract monocytes, eosinophils or basophils; the g -chemokines have only one cysteine pair and are chemotactic for lymphocytes (lymphotactin), the d -chemokines are structurally rather different being membrane-anchored, have a C-X-X-X-C motif and are restricted (so far) to brain (neurotactin). Human genes for the a -chemokines are on Chr 4 and 10, for b -chemokines on Chr 17, for lymphotactin on Chr 1 and for neurotactin on Chr16. The receptors are G-protein coupled.