| Primary Identifier | IPR026296 | Type | Family |
| Short Name | CXCL16 |
| description | Chemokines are proteins that have important physiological and pathophysiological roles in a wide range of acute and chronic inflammatory processes []. Chemokines exert their biological effects by binding to cell surface receptors. Their sequences are similar and are characterised by a 4-cysteine motif: the family can be divided according to whether the first 2Cys residues are adjacent (the C-C family), separated by an intervening residue (the C-x-C family), have only one of the first two Cys residues (C chemokines), or contain both cysteines, separated by threeintervening residues (C-x3-C chemokines). This entry represents a novel chemokine, chemokine (C-X-C motif) ligand 16 (CXCL16), has been identified that is a member of the C-X-C family [, ], it is also called SR-PSOX. Despite possessing the CXC motif, however, it is distantly related to the other family members and has greatest sequence similarity to members of the C-C family []. CXCL16 also differs in structure from the other family members (all of which are secreted proteins) and contains a TM domain linked to the chemokine domain by a heavily glycosylated mucin stalk. This structure is similar to that of the CX3C chemokine ligand 1 (CX3C chemokine fractalkine), the only other known chemokine with a TM domain. CXCL16 has been found to be expressed in the spleen, lymph nodes, Peyer's patches and thymus. In non-lymphoid tissues, CXCL16 is found in the lung, small intestine, kidney, heart and liver []. The chemokine appears to be expressed as a membrane-bound cell surface ligand on antigen presenting cells (APCs), such as B cells and macrophages []. CXCL16 can also be shed from the cell surface in an active, soluble form [, ]. These two forms may have different functions. Expression of CXCL16 is upregulated by exposure to inflammatory stimuli.CXCL16 induces a strong chemotactic response. It induces calcium mobilisation and binds to chemokine receptor CXCR6 and HIV-coreceptor Bonzo [, ]. It also acts as a scavenger receptor on macrophages, which specifically binds to OxLDL (oxidized low density lipoprotein), suggesting that it may be involved in pathophysiology such as atherogenesis []. Expression of CXCL16 is induced by the inflammatory cytokines IFN-gamma and TNF-alpha []. |
