Schultz et al. (1998) Proc. Natl. Acad. Sci. USA 95, 5857-5864
Letunic et al. (2012) Nucleic Acids Res , doi:10.1093/nar/gkr931

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IL2 Interleukin-2 family

SMART accession number:	SM00189
Description:	Interleukin-2 is a cytokine produced by T-helper cells in response to antigenic or mitogenic stimulation. This protein is required for T-cell proliferation and other activities crucial to the regulation of the immune response.
Interpro abstract (IPR000779):	T-Lymphocytes regulate the growth and differentiation of certain lymphopoietic and haemopoietic cells through the release of various secreted protein factors [(PUBMED:3918306)]. These factors, which include interleukin-2 (IL2), are secreted by lectin- or antigen-stimulated T-cells, and have various physiological effects. IL2 is a lymphokine that induces the proliferation of responsive T-cells. In addition, it acts on some B-cells, via receptor-specific binding [(PUBMED:3517854)], as a growth factor and antibody production stimulant [(PUBMED:1510960)]. The protein is secreted as a single glycosylated polypeptide, and cleavage of a signal sequence is required for its activity [(PUBMED:3517854)]. Solution NMR suggests that the structure of IL2 comprises a bundle of 4 helices (termed A-D), flanked by 2 shorter helices and several poorly-defined loops. Residues in helix A, and in the loop region between helices A and B, are important for receptor binding. Secondary structure analysis has suggested similarity to IL4 and granulocyte-macrophage colony stimulating factor (GMCSF) [(PUBMED:1510960)].
GO process:	immune response (GO:0006955)
GO component:	extracellular region (GO:0005576)
GO function:	growth factor activity (GO:0008083), interleukin-2 receptor binding (GO:0005134)
Family alignment:	View or CHROMA formatCLUSTALW formatMSF formatFASTA formatPIR format

There are 61 IL2 domains in 61 proteins in SMART's nrdb database.

Click on the following links for more information.

• Evolution (species in which this domain is found)

• Click on to expand nodes. To display all proteins with a IL2 domain in a specific node, click on it.

  This tree shows only several representative species. The complete taxonomic breakdown of all proteins with IL2 domain is also avaliable.

  Useful shortcuts: Expand all nodes or Collapse tree
  Go to specific node: Homo sapiens, Mus musculus, Rattus norvegicus

• Metabolism (metabolic pathways involving proteins which contain this domain)

• % proteins involved KEGG pathway ID Description 33.33 map04940 Type I diabetes mellitus 33.33 map04060 Cytokine-cytokine receptor interaction 33.33 map04660 T cell receptor signaling pathway This information is based on mapping of SMART genomic protein database to KEGG orthologous groups. Percentage points are related to the number of proteins with IL2 domain which could be assigned to a KEGG orthologous group, and not all proteins containing IL2 domain. Please note that proteins can be included in multiple pathways, ie. the numbers above will not always add up to 100%.

• Structure (3D structures containing this domain)

• 3D Structures of IL2 domains in PDB

  PDB code	Main view	Title
  1irl		The solution structure of the f42a mutant of human interleukin 2
  1m47		Crystal structure of human interleukin-2
  1m48		Crystal structure of human il-2 complexed with (r)-n-[2-[1- (aminoiminomethyl)-3-piperidinyl]-1-oxoethyl]-4- (phenylethynyl)-l-phenylalanine methyl ester
  1m49		Crystal structure of human interleukin-2 complexed with sp-
  1m4a		Crystal structure of human interleukin-2 y31c covalently modified at c31 with (1h-indol-3-yl)-(2-mercapto- ethoxyimino)-acetic acid
  1m4b		Crystal structure of human interleukin-2 k43c covalently modified at c43 with 2-[2-(2-cyclohexyl-2-guanidino- acetylamino)-acetylamino]-n-(3-mercapto-propyl)- propionamide
  1m4c		Crystal structure of human interleukin-2
  1nbp		Crystal structure of human interleukin-2 y31c covalently modified at c31 with 3-mercapto-1-(1,3,4,9-tetrahydro-b- carbolin-2-yl)-propan-1-one
  1pw6		Low micromolar small molecule inhibitor of il-2
  1py2		Structure of a 60 nm small molecule bound to a hot spot on il-2
  1qvn		Structure of sp4160 bound to il-2 v69a
  1z92		Structure of interleukin-2 with its alpha receptor
  2b5i		Cytokine receptor complex
  2erj		Crystal structure of the heterotrimeric interleukin-2 receptor in complex with interleukin-2
  3ink		Unraveling the structure of interleukin-2: reply

• Links (links to other resources describing this domain)

• BLOCKS	INTERLEUKIN_2
  PFAM	Interleukin2
  INTERPRO	IPR000779
  PROSITE	INTERLEUKIN_2

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