Recombinant Mouse IL-12 R beta 1 Protein, CF

IL-12 R beta1 is a 100 kDa type I transmembrane protein that belongs to the gp130/G-CSF R family of cytokine receptors. IL-12 R beta1 is a common subunit of both the IL-12 and IL-23 receptor complexes which play distinct but related roles in T cell mediated inflammatory reactions (1, 2). Mature mouse IL-12 R beta1 contains a 546 amino acid (aa) extracellular domain (ECD) with five fibronectin type III repeats, and a 147 aa cytoplasmic domain (3). Within the ECD, mouse IL-12 R beta1 shares 85% and 52% aa sequence identity with rat and human IL-12 R beta1, respectively. It shares 16% - 21% aa sequence identity with the ECDs of mouse gp130, LIF R, G-CSF R, and IL-23 R. IL-12 and IL-23 are disulfide linked heterodimeric cytokines that share a common p40 subunit (1, 2). IL-12 R beta1 interacts with p40 at low affinity but does not transmit signals (3). Increased ligand binding affinity and signaling capacity are gained by association of IL-12 R beta1 with either IL-12 R beta2 or IL-23 R (4 - 6). IL-12 R beta2 and IL-23 R are the signal transducing components of these receptor complexes (4, 7). IL-12 R beta1 is expressed on activated T cells, NK cells, B cells, macrophages, and microglia (8 - 10). IL-12 induced signaling promotes the development of naïve T cells into IFN-beta producing Th1 cells (11). IL-23 contributes to chronic inflammation by inducing the production of IL-17 by memory T cells (12). Naturally occurring homodimers of p40 can function as antagonists of IL-12 and IL-23 and can also induce macrophage chemotaxis in the absence of IL-12 R beta2 (13, 14).