Interleukin-1 Receptor Type 1 (IL-1R1)

Interleukin-1 receptor type 1 (IL-1R1), also known as CD121a, is a transmembrane cytokine receptor that plays a central role in mediating immune and inflammatory responses. It is the primary signaling receptor for interleukin-1 alpha (IL-1α) and interleukin-1 beta (IL-1β). The extracellular region of IL-1R1 consists of three immunoglobulin-like domains that bind IL-1α and IL-1β, initiating a signaling cascade through the TIR domain, leading to NFκB activation and inflammatory responses. IL-1R1 is constitutively expressed on various cell types, including T cells, endothelial cells, and fibroblasts, and its expression can be upregulated during inflammation or immune activation. The interleukin 1 receptor antagonist (IL-1Ra) also binds to IL-1R1, blocking activation and serving as a natural antagonist to limit excessive inflammation.

Other names

CD121a

IL-1Ra competes with IL-1α and IL-1β for binding to IL-1R1, preventing receptor activation and downstream signaling.