IL-1R1/CD121a

IL-1R1 (CD121a), a member of IL-1 receptor, is a receptor for IL-1α, IL-1β, IL-1Ra and IL-38[1]. IL-1R1 mediates immune and inflammatory responses.IL-1R1 mediates IL-1-dependent activation, including the activation of NF-κB and MAPK pathway[2]. IL-1R1 is expressed in specific endothelial cells, ventricular cells, astrocytes, and neurons[3]. Human IL-1R1 consists of extracellular domain (L18-K336), helical domain (H337-Y356), and cytoplasmic domain (K357-G569).Human IL-1R1 shares <70% aa sequence identity with mouse and rats. Rats IL-1R1 shares 85.59% aa sequence identity with mouse. IL-1R1 binds to IL-1 by forming a heterodimer with IL-1R3 (IL-1RAcP). The heterodimer is responsible for the signal transduction by the hydrolysis of GTP, followed by the activation of JNK and p38 MAP kinase[4]. Upon binding of IL-1, IL-1R1 initiates the downstream signaling cascade (MAPK p38 and NF-κB pathway)[2].