CD213a2 IL13Rα 2 (interleukin 13 receptor, α2)
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 1 glycoprotein
B Cell
Monocyte
Colon
Endothelial Cell
Lymphocyte
Dendritic Cell
Blood Cell, Peripheral
Tonsil
Fibroblast
60 / 60
70 / 70

Expression
CD213a2 is expressed on B cells, monocytes, fibroblasts and endothelial cells.  CD213a2 is also expressed on cord blood, a subset peripheral blood lymphocytes, subpopulations of peripheral blood lymphocytes, immature dendritic cells and subsets of B lymphocytes from tonsil, blood and colon. 


Structure
MOLECULAR FAMILY NAME: Belongs to the type-1 cytokine receptor family.

CD213ais a single-pass type-1 354 aa glycoprotein.  It contains a putative 26 aa signal peptide, a 317 aa extracellular domain with a fibronectin-like type-3 domain and typical cytokine receptor motifs, a 20 aa transmembrane region and a short 17 aa intracellular cytoplasmic domain.  The extracellular domain is closely related to that of CD213a1 but the residue cytoplasmic domain is much shorter suggesting that the 2 receptors are functional distinct.   It is structurally similar to the CD125 (IL-5a) chain with a 51% aa sequence similarity and a 27% identity.  Similar to CD125, the extracellular region of the CD213α2 chain consists of a N-terminal region of about 100 aa with a sequence similarity to the equivalent portion of the CD123 (IL-3Ra) chain and the CD116 (GM-CSFRa) chain, followed by a cytokine receptor domain and a fibronectin type 3 domain that includes the WSXWS motif.  The WSXWS motif appears to be necessary for protein protein folding and thereby efficient intracellular transport and cell-surface receptor binding.

MOLECULAR MASS
Cell Type Unreduced Reduced
60 - 70 kDa

POST-TRANSCRIPTIONAL MODIFICATION

Human CD213a2 contains a putative consensus phosphorylation site that may interact with SH2 containing signaling molecules.

POST-TRANSLATIONAL MODIFICATION OF CD213a2

CD213a2 has a 27 aa N-terminal residue of human and mouse which is nearly identical.


Ligands
The human IL-13Ra chain is expressed in COS-7 cells binds human IL-13 with a high affinity of kDa = 220-280 pM, whereas COS-7 cells transfected with the mouse IL-13Ra chain cDNA bind mouse IL-13 with a low affinity of kDa = 2-10 pM. In both species, the IL-13Ra chain also associates with CD124 to form a receptor capable of binding both IL-13 and IL-4 with a high affinity and mediating signal transduction events.  This interaction may explain the apparent discrepancy in the ability of the human, but not mouse, IL-13Ra chain to bind IL-13 with a high affinity.  Untransfected COS-7 cells express low levels of CD124 which might associate with the transfected human, but not mouse, IL-13Ra chain to form a functional high-affinity binding site for IL-13.  Crosslinking experiments have identified an IL-13 binding protein of approximately 60 kDa-70 kDa, which probably corresponds to the IL-13Ra chain.


Function
IL-13 binds cells through either a combination with CD213α1 and CD124 or through CD213α2.  In both cases, the common γ chain appears to be necessary for signaling.  IL-13 though its receptors regulates, inflammation, cell signaling and immune regulation.  It inhibits the production of pro-inflammatory cytokines and chemokines from monocytes and macrophages.  IL-13 upregulates several cell-surface molecules, including MHC class II and CD23 and it can act as a costimulus for B-cell proliferation and Ig synthesis and class switching.  IL-13 is not restricted in function to lymphocytes and has activities on progenitor cells and endothelial.  CD213a2 receptors are involved in cell signaling and immune regulation.  There is a novel mechanism by which IFN-g can regulate IL-13 responses.  CD213a2 inhibits binding of IL-13 to the IL-13 cell surface receptor.  IL-13 and IL-4 mediate similar biological functions except that they do not regulate T cell functions.  The protein encoded by CD213α2 is closely related to CD213α1, a subunit of the IL-13 receptor complex.  The protein binds IL-13 with high affinity but not IL-4 and lacks the cytoplasmic domain, and does not appear to function as a signal mediator.  It is reported to play a role in the internalization of IL-13.

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD213a2 IN INTACT ANIMAL

CD213α2 can reverse IL-13 airway hyper-responsiveness, suggesting a possible use in asthma.

Comments
The human and mouse IL-13Ra chain sequences share the same overall topology, but show only limited aa sequence identity.  It remains to be determined whether additional IL-13R subunits exist and whether, in fact, these molecules are true species orthologues.  The accession numbers and aa sequences are given in CD124.

MOLECULAR INTERACTIONS -
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD213a2 : No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD213a2 : No information.


Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 3598Q14627
Antibodies

Revised June 25, 2008


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