|CD25||Tac antigen, IL-2Rα chain|
|Molecule Type||Antigen Expression||Molecular Weight|
Min / Max
|Non-lineage Restricted Molecule|
Type 1 glycoprotein
|55 / 55|
|The IL-2R is expressed on activated cells including T and B cells and monocytes. The CD25 subunit of the human IL-2R is also present on a subset of thymocytes, HTLV-1 transformed T and B cells, EBV transformed B cells, myeloid precursors and oligodendrocytes. IL-2 induces the expression of the CD25 subunit on NK cells. CD25 is expressed, typically at high levels, on PHA-stimulated T cells, on B cells stimulated with anti-IgM antibody, on monocytes/macrophages stimulated with LPS and highly expressed on HTLV-1-transformed T cell lines. CD25 is proteolytically released from lymphoid cells and is found in serum but is detected at a low level in a subset of resting T cells|
|MOLECULAR FAMILY NAME: Belongs to the cytokine receptor family.|
CD25 is a single-pass type-1 a chain 272 aa glycoprotein. It contains an extracellular domain which contains 2 complement control protein (CCP) domains and an extensively N- and O-linked carbohydrate glycosylation sites, a transmembrane domain and a short 13 aa cytoplasmic domain. The IL-15R a chain is structurally related to CD25, the IL-2Rα chain. Proteolytic cleavage of membrane-bound CD25 generates a soluble form present in human serum. The functional high affinity of IL-2R with kDa = 10 pM is composed of a non-covalently associated CD25/CD122/CD132 (IL-2Rα/IL-2Rβ/IL-2Rγ) heterotrimer. The isolated CD25 subunit constitutes a low-affinity IL-2R with kDa = 10 nM.
Alternatively spliced CD25 mRNA have been isolated but the significance is presently unknown.
POST TRANSLATIONAL MODIFICATION
CD25 is highly N-glycosylated and O-glycosylated. Soluble CD25 is produced from CD25 by proteolytic cleavage.
|CD25 is the α-chain of a three-chain receptor for IL-2. CD25 does bind IL-2 by itself but with low affinity.|
LIGANDS AND MOLECULES ASSOCIATED WITH CD25
|CD25 contains an α-chain which is a low-affinity IL-2 receptor and a β-chain which is a medium-affinity receptor and an activation marker which induces the activation and proliferation of T cells, thymocytes, NK cells, B cells and macrophages. By noncovalently associating with CD122 and CD132 (which can also combine with CD124 and CD217 to form the IL-4 and IL-7 receptors), it forms the high affinity IL-2 receptor complex. CD4+CD25+ regulatory T cells seem to regulate other T cells and play a role in limiting inflammatory responses and preventing autoimmunity as knockout mice develop autoimmune diseases. CD25 also associates with β and γ chains to form high affinity with IL-2R. CD25 plays a role in T cell mediated immune response and is phosphorylated on Ser and Thr residues. CD25 is membrane-bound and soluble and is used to monitor cell activation in immune response. |
BIOCHEMICAL ACTIVITY: No information.
DISEASE RELEVANCE AND FUNCTION OF CD25 IN INTACT ANIMAL
In 4 lines of human adult T cell lymphoma leukemia origin, 3 CD25 subunits are compartmented together with HLA glycoproteins and CD48 molecules in the plasma membrane.
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD25
SUBSTRATE: No information.
ENZYMES WHICH MODIFY CD25: No information.
Database accession numbers
Revised June 25, 2008