Interleukin-1 homologues
SMART accession number:SM00125
Description: Cytokines with various biological functions. Interluekin 1 alpha and beta are also known as hematopoietin and catabolin.
Interpro abstract (IPR000975):

Interleukin-1 alpha and interleukin-1 beta (IL-1 alpha and IL-1 beta) are cytokines that participate in the regulation of immune responses, inflammatory reactions, and hematopoiesis [(PUBMED:2969618)]. Two types of IL-1 receptor, each with three extracellular immunoglobulin (Ig)-like domains, limited sequence similarity (28%) and different pharmacological characteristics have been cloned from mouse and human cell lines: these have been termed type I and type II receptors [(PUBMED:8702856)]. The receptors both exist in transmembrane (TM) and soluble forms: the soluble IL-1 receptor is thought to be post-translationally derived from cleavage of the extracellular portion of the membrane receptors.

Both IL-1 receptors appear to be well conserved in evolution, and map to the same chromosomal location [(PUBMED:1833184)]. The receptors can both bind all three forms of IL-1 (IL-1 alpha, IL-1 beta and IL-1RA).

The crystal structures of IL1A and IL1B [(PUBMED:2602367)] have been solved, showing them to share the same 12-stranded beta-sheet structure as both the heparin binding growth factors and the Kunitz-type soybean trypsin inhibitors [(PUBMED:1738162)]. The beta-sheets are arranged in 3 similar lobes around a central axis, 6 strands forming an anti-parallel beta-barrel. Several regions, especially the loop between strands 4 and 5, have been implicated in receptor binding.

The Vaccinia virus genes B15R and B18R each encode proteins with N-terminal hydrophobic sequences, possible sites for attachment of N-linked carbohydrate and a short C-terminal hydrophobic domain [(PUBMED:1826022)]. These properties are consistent with the mature proteins being either virion, cell surface or secretory glycoproteins. Protein sequence comparisons reveal that the gene products are related to each other (20% identity) and to the Ig superfamily. The highest degree of similarity is to the human and murine interleukin-1 receptors, although both proteins are related to a wide range of Ig superfamily members, including the interleukin-6 receptor. A novel method for virus immune evasion has been proposed in which the product of one or both of these proteins may bind interleukin-1 and/or interleukin-6, preventing these cytokines reaching their natural receptors [(PUBMED:1826022)]. A similar gene product from Cowpox virus (CPV) has also been shown to specifically bind murine IL-1 beta [(PUBMED:1339315)].

This entry represents Interleukin-1.

GO component:extracellular space (GO:0005615)
Family alignment:
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There are 914 IL1 domains in 903 proteins in SMART's nrdb database.

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