What Are Chemokines?

Chemokines are a class of small cytokines or signaling proteins secreted by cells. Because they have the ability to induce directional chemotaxis in nearby responding cells, they are named chemokines.

Chemokine

Chemokines are a class of small cytokines or signaling proteins secreted by cells. Because they have the ability to induce directional chemotaxis in nearby responding cells, they are named chemokines.
Chinese name
Chemokine
Foreign name
chemokines
nickname
Chemokine
Molecular weight
8-10 kDa
Features
Directed chemotactic
Nature
protein
When the human body defends and removes foreign bodies such as invading pathogens, it has a function to orient chemotaxis of immune cells. Some substances can cause this function to be called chemokines or chemokines.
The main role of chemokines is to induce directional migration of cells, and cells attracted by chemokines migrate to the source of chemokines along the signal of increasing chemokine concentration. Some chemokines
Chemokine receptors are G protein-coupled receptors containing seven transmembrane domains found on the surface of white blood cells. To date, about 19 different chemokine receptors have been identified. According to the type of chemokine they bind, they are divided into four families: CXCR that binds to CXC chemokines, and CC chemokines CCR, CX3CR1 that binds to the sole CX3C chemokine (CX3CL1), and XCR1 that binds to two XC chemokines (XCL1 and XCL2). They have many common structural characteristics: they are similar in size (about 350 amino acids), have a short acidic N-terminus, 7 helical transmembrane domains, 3 intracellular and 3 extracellular hydrophilic rings, and One contains the C-terminus of serine and threonine residues important for receptor regulation. The first two extracellular loop chemokine receptors each have a conserved cysteine residue, allowing these loops to form a disulfide bond. G protein is coupled to the C-terminus of the chemokine receptor, which enables intracellular signaling after the receptor is activated, and the N-terminal domain of the chemokine receptor determines the specificity of ligand binding.

Chemokine signal transduction

The chemokine receptor binds to the G protein and transmits cellular signals. The G protein is activated by chemokine receptors, causing subsequent activation of an enzyme called phospholipase C (PLC). PLC splits a molecule called phosphatidylinositol (4,5) -bisphosphate (PIP2) into two second messenger molecules, called inositol triphosphate (IP3) and diacylglycerol (DAG), thereby Trigger intracellular signaling events; DAG activates another enzyme called protein kinase C (PKC), while IP3 triggers intracellular calcium release. These events promote many signaling cascades (such as the MAP kinase pathway), resulting in changes in chemotaxis, degranulation, release of superoxide anions, and changes in the activity of adhesion molecules (called integrins) that contain chemokine receptors in cells.

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