In this article we will discuss Chemokines. So, let’s get started.
Chemokines are a family of small, 8-10 kD proteins that act primarily as chemoattractants for specific leukocytes. They bind to seven transmembrane G protein-coupled receptors. There are 40 different types of chemokines and 20 different types of chemokine receptors. Chemokines are classified into four groups based on the arrangement of conserved cysteine residues in the proteins, namely,
1. CXC chemokines or a-chemokines
(a) One amino acid residue separates first two conserved cysteine residues.
(b) Typical example is ILS. IL8 is secreted by macrophages and endothelial cells and primarily acts on neutrophils (activation and chemotaxis of neutrophils).
2. CC chemokines or B-chemokines
(a) Two conserved cysteine residues are located adjacent to each other.
(b) Include MCP-1, eotaxin, MIP-a, and RANTES (regulated and normal T cell expressed and secreted).
(c) Chemotactic for monocytes, eosinophils, basophils and lymphocytes (not neutrophils).
3. C chemokines or y-chemokines: Lack first and third (two of four) cysteines, for example lymphotactin specific for lymphocytes.
4. CX,C chemokines: Three amino acid residues between two cysteines, for example fractalkine.