This is the C-terminal domain of Innate Immune Pattern-Recognition Receptor RIG-I present in homo sapiens. RIG-I is a key cytosolic pattern-recognition receptors of the vertebrate innate immune system that form the first line of defense against RNA viral infection. RNA binding to RIG-I is mediated both by the C-terminal domain and by the helicase domain. The C-terminal domain specifically binds the 5'triphosphate end with a 10-fold higher affinity compared to 5'OH-dsRNA [1].

1: Structural basis for the activation of innate immune pattern-recognition receptor RIG-I by viral RNA. Kowalinski E, Lunardi T, McCarthy AA, Louber J, Brunel J, Grigorov B, Gerlier D, Cusack S; Cell. 2011;147:423-435. PMID:22000019