Interleukin-6 homologues
SMART accession number:SM00126
Description: Family includes granulocyte colony-stimulating factor (G-CSF) and myelomonocytic growth factor (MGF). IL-6 is also known as B-cell stimulatory factor 2.
Interpro abstract (IPR003573):

Interleukin-6 (IL6), also refered to as B-cell stimulatory factor-2 (BSF-2) and interferon beta-2, is a cytokine involved in a wide variety of biological functions [(PUBMED:3491322)]. It plays an essential role in the final differentiation of B-cells into IG-secreting cells, as well as inducing myeloma/plasmacytoma growth, nerve cell differentiation and, in hepatocytes, acute phase reactants [(PUBMED:3491322), (PUBMED:2037043)].

A number of other cytokines may be grouped with IL6 on the basis of sequence similarity [(PUBMED:3491322), (PUBMED:2037043), (PUBMED:2472117)]: these include granulocyte colony-stimulating factor (GCSF) and myelomonocytic growth factor (MGF). GCSF acts in hematopoiesis by affecting the production, differentiation and function of 2 related white cell groups in the blood [(PUBMED:2472117)]. MGF also acts in hematopoiesis, stimulating proliferation and colony formation of normal and transformed avian cells of the myeloid lineage.

Cytokines of the IL6/IL23/GCSF/MGF are glycoproteins of about 170 to 180 amino acid residues that contains four conserved cysteine residues involved in two disulphide bonds [(PUBMED:2472117)]. They have a compact, globular fold (similar to other interleukins), stabilised by the 2 disulphide bonds. One half of the structure is dominated by a 4 alpha-helix bundle with a left-handed twist [(PUBMED:1400355)]: the helices are anti-parallel, with 2 overhand connections, which fall into a 2-stranded anti-parallel beta-sheet. The fourth alpha-helix is important to the biological activity of the molecule [(PUBMED:2037043)].

It has been said [(PUBMED:1717982)] that this family can be extended by the adjunction of LIF and OSM (see the relevant entry IPR001581) which seem to be structurally related.

GO process:immune response (GO:0006955)
GO component:extracellular region (GO:0005576)
GO function:cytokine activity (GO:0005125)
Family alignment:
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There are 239 IL6 domains in 239 proteins in SMART's nrdb database.

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