CX3CL1
Description
The CX3CL1 (C-X3-C motif chemokine ligand 1) is a protein-coding gene located on chromosome 16.
Fractalkine, also known as chemokine (C-X3-C motif) ligand 1, is a protein that in humans is encoded by the CX3CL1 gene. Fractalkine is a large cytokine protein of 373 amino acids that contains multiple domains and is the only known member of the CX3C chemokine family. It is also commonly known under the names fractalkine (in humans) and neurotactin (in mice). The polypeptide structure of CX3CL1 differs from the typical structure of other chemokines. For example, the spacing of the characteristic N-terminal cysteines differs; there are three amino acids separating the initial pair of cysteines in CX3CL1, with none in CC chemokines and only one intervening amino acid in CXC chemokines. CX3CL1 is produced as a long protein (with 373-amino acid in humans) with an extended mucin-like stalk and a chemokine domain on top. The mucin-like stalk permits it to bind to the surface of certain cells. However, a soluble (90 kD) version of this chemokine has also been observed. Soluble CX3CL1 potently chemoattracts T cells and monocytes, while the cell-bound chemokine promotes strong adhesion of leukocytes to activated endothelial cells, where it is primarily expressed. CX3CL1 elicits its adhesive and migratory functions by interacting with the chemokine receptor CX3CR1.
CX3CL1, also known as Fractalkine, is a chemokine that acts as a ligand for both CX3CR1 and integrins ITGAV:ITGB3 and ITGA4:ITGB1. The CX3CR1-CX3CL1 signaling pathway plays a crucial role in various processes including immune response, inflammation, cell adhesion, and chemotaxis. It regulates leukocyte adhesion and migration at the endothelium. CX3CL1 can activate integrins in both a CX3CR1-dependent and CX3CR1-independent manner. In the presence of CX3CR1, it activates integrins by binding to the classical ligand-binding site (site 1). In the absence of CX3CR1, CX3CL1 binds to a second site (site 2) which enhances the binding of other integrin ligands to site 1.
CX3CL1 is also known as ABCD-3, C3Xkine, CXC3, CXC3C, NTN, NTT, SCYD1, fractalkine, neurotactin.
