Interleukin-4 receptor

The interleukin 4 receptor is a is_associated_with::type I cytokine receptor. IL4R is its human is_associated_with::gene.

Function
This gene encodes the alpha chain of the interleukin-4 receptor, a type I transmembrane protein that can bind is_associated_with::interleukin 4 and is_associated_with::interleukin 13 to regulate IgE is_associated_with::antibody production in is_associated_with::B cells. Among is_associated_with::T cells, the encoded protein also can bind interleukin 4 to promote differentiation of is_associated_with::Th2 cells. A soluble form of the encoded protein can be produced by an alternate splice variant or by proteolysis of the membrane-bound protein, and this soluble form can inhibit IL4-mediated cell proliferation and IL5 upregulation by T-cells. Allelic variations in this gene have been associated with atopy, a condition that can manifest itself as allergic rhinitis, sinusitis, asthma, or eczema. Two transcript variants encoding different isoforms, a membrane-bound and a soluble form, have been found for this gene.

The binding of IL-4 or IL-13 to the IL-4 receptor on the surface of is_associated_with::macrophages results in the alternative activation of those macrophages. Alternatively activated macrophages (AAMΦ) downregulate inflammatory mediators such as is_associated_with::IFNγ during immune responses, particularly with regards to is_associated_with::helminth infections.

Interactions
Interleukin-4 receptor has been shown to interact with is_associated_with::SHC1.

Structure
The is_associated_with::N-terminal (is_associated_with::extracellular) portion of interleukin-4 receptor is related in overall topology to is_associated_with::fibronectin type III modules and folds into a sandwich comprising seven antiparallel is_associated_with::beta sheets arranged in a three-strand and a four-strand is_associated_with::beta-pleated sheet. They are required for binding of interleukin-4 to the receptor alpha chain, which is a crucial event for the generation of a is_associated_with::Th2-dominated early is_associated_with::immune response.