IL-4 is a pleiotropic cytokine produced by activated T cells. The IL-4 receptor also binds to IL-13, which may contribute many overlapping functions of IL-4 and IL-13. STAT6, a signal transducer and activator of transcription, is important in mediating the immune regulatory signal of this cytokine. This gene, IL-3, IL-5, IL-13, and CSF2 form a cytokine gene cluster on chromosome 5q. IL-4, IL-13 and IL-5 are found to be regulated coordinately by several long-range regulatory elements in an over 120 kilobase range on the chromosome. Two alternatively spliced transcript variants of this gene encoding distinct isoforms have been reported.

Expression System
Escherichia coli

Sequence
MHKCDITLQEIIKTLNSLTEQKTLCTELTVTDIFAASKNTTEKETFCRAATVLRQFYSHHEKDTRCLGATAQQFHRHKQLIRFLKRLDRNLWGLAGLNSCPVKEANQSTLENFLERLKTIMREKYSKCSS with polyhistidine tag at the C-terminus

Species
Human

Tag
polyhistidine tag at the C-terminus

Endotoxin Level
<0.1 EU per 1 μg of the protein by the LAL method.

Activity
Measure by its ability to induce TF-1 cells proliferation.
The ED₅₀ for this effect is <0.2 ng/mL.
The specific activity of recombinant human IL-4 is approximately >2.8 x 10⁷ IU/mg.

Purity
>98% as determined by SDS-PAGE. Ni-NTA chromatography

Formulation
The protein was lyophilized from a solution containing 1X PBS, pH 8.0.

Reconstitution
It is recommended to reconstitute the lyophilized protein in sterile H₂O to a concentration not less than 100 μg/mL and incubate the stock solution for at least 20 minutes to ensure sufficient re-dissolved.

SDS-PAGE analysis of recombinant human IL-4