Interleukin 12 subunit beta

Subunit beta of interleukin 12 (also known as IL-12B, natural killer cell stimulatory factor 2, or cytotoxic lymphocyte maturation factor 2, p40) is a is_associated_with::protein that in humans is encoded by the IL12B is_associated_with::gene. IL-12B is a subunit of is_associated_with::interleukin 12.

Function
This gene encodes a subunit of is_associated_with::interleukin 12, a is_associated_with::cytokine that acts on T and is_associated_with::natural killer cells, and has a broad array of biological activities. Interleukin 12 is a disulfide-linked heterodimer composed of the 40 kD is_associated_with::cytokine receptor like subunit encoded by this gene, and a 35 kD subunit encoded by IL12A. This cytokine is expressed by activated is_associated_with::macrophages that serve as an essential inducer of is_associated_with::Th1 cells development. This cytokine has been found to be important for sustaining a sufficient number of memory/effector Th1 cells to mediate long-term protection to an intracellular pathogen. is_associated_with::Overexpression of this gene was observed in the central nervous system of patients with multiple sclerosis (MS), suggesting a role of this cytokine in the pathogenesis of the disease. The promoter gene polymorphism of this gene has been reported to be associated with the severity of atopic and non-atopic is_associated_with::asthma in children.

Structure
Editing results in an amino acid change from an alanine to a valine may cause a conformational change in the IL12 receptor.

Function
Editing causes a reduction in the extent of IL-12 signaling as the β subunit is involved in signal transduction. This leads to insufficient IFN-γ production, possibly due to an interruption of the binding of IL-12 to its receptor. Binding may be restricted due to a conformational change caused by the change of amino acid. The change in the signaling cascade and reduction of IFN-γ effects downregulation of IgE. Atrophy patients have enhanced IgE sensitivity to everyday environmental factors such as asthma. This is the only editing event linked to atrophy.

RNA editing
Interleukin 12 receptor, beta 2 subunit(IL12Rβ2) is a product of the IL12-R β2 gene. As previously mentioned, the gene product is one of two subunits which combine to form the IL-12 receptor.The other subunit being IL12-R β1 subunit. The β2 subunit is only expressed in Th1 lymphocytes.The pre-mRNA of the IL12-R β2 gene is subject to RNA editing.

Editing type
Cytidine to Uridine (C to U) RNA editing.

Editing sites
The editing site is located at nucleotide 2451 which is found in exon 13 which forms part of the extracellular domain of the protein. However another report was unable to detect this C to U conversion

Role as IL-23 subunit
Interleukin-12 p40 also serves as a subunit of is_associated_with::Interleukin 23.

Clinical significance
There is an increase in the frequency of editing in is_associated_with::Atopic patients (20.6%) from that non atopic patients (3.8%) transcripts.This is the first reported case that  indicates that atopy could be  associated with RNA editing.Atopy is characterized by enhanced immunoglobulin E (IgE) responses to common environmental antigens and leads to clinical disorders such as asthma, eczema and rhinitis.