Mature mouse IL-2 shares 56% and 73% aa sequence identity with human and rat IL-2, respectively. It shows strain-specific heterogeneity in an N-terminal region that contains a poly-glutamine stretch. Mouse and human IL-2 exhibit cross-species activity. The receptor for IL-2 consists of three subunits that are present on the cell surface in varying preformed complexes . The 55 kDa IL-2 Rαis specific for IL-2 and binds with low affinity. The 75 kDa IL-2 Rbeta, which is also a component of the IL-15 receptor, binds IL-2 with intermediate affinity. The 64 kDa common gamma chainγc/IL-2 Rγ, which is shared with the receptors for IL-4, -7, -9, -15, and -21, does not independently interact with IL-2. Upon ligand binding, signal transduction is performed by both IL-2 Rbetaandγc. It drives resting T cells to proliferate and induces IL-2 and IL-2 Rαsynthesis. It contributes to T cell homeostasis by promoting the Fas-induced death of naA??ve CD4+ T cells but not activated CD4+ memory lymphocytes . IL-2 plays a central role in the expansion and maintenance of regulatory T cells, although it inhibits the development of Th17 polarized cells. Synonym: Interleukin-2 ( IL-2 ), Mouse. Formulation: Lyophilized from a 0.2μm filtered solution in PBS, pH 7.4.