CXC chemokine 16 (IPR026296)

Short name: CXCL16

Overlapping homologous superfamilies


Family relationships



Chemokines are proteins that have important physiological and pathophysiological roles in a wide range of acute and chronic inflammatory processes [PMID: 11544102]. 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 2 Cys 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 three intervening 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 [PMID: 11017100, PMID: 11290797], 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 [PMID: 11290797]. 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 [PMID: 11017100]. The chemokine appears to be expressed as a membrane-bound cell surface ligand on antigen presenting cells (APCs), such as B cells and macrophages [PMID: 11290797]. CXCL16 can also be shed from the cell surface in an active, soluble form [PMID: 11017100, PMID: 11290797]. 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 [PMID: 11017100, PMID: 11290797]. 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 [PMID: 11060282]. Expression of CXCL16 is induced by the inflammatory cytokines IFN-gamma and TNF-alpha [PMID: 15128827].

GO terms

Biological Process

GO:0006935 chemotaxis
GO:0048247 lymphocyte chemotaxis
GO:0030307 positive regulation of cell growth
GO:0030335 positive regulation of cell migration
GO:0006898 receptor-mediated endocytosis
GO:0034097 response to cytokine
GO:0034341 response to interferon-gamma
GO:0034612 response to tumor necrosis factor

Molecular Function

GO:0008009 chemokine activity
GO:0005041 low-density lipoprotein particle receptor activity
GO:0005044 scavenger receptor activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.