Toll-like receptor 3 (TLR3), also known as CD283, is type I transmembrane protein that belongs to the TLR family. It forms a large horseshoe shape that contacts a neighboring horseshoe, forming a dimer of two horseshoes. It is characterized by an extracellular domain with leucine-rich repeats and a cytoplasmic domain with homology to the type I IL-1 receptor. TLR3 is expressed selectively on the cytoplasmic membrane and intracellularly in dendritic cells. It is also highly expressed in the placenta, pancreas, heart, liver, lung, and muscle. TLR3 is a pattern recognition receptor that participates in innate immune response to microbial pathogens by recognizing polyinosine-polycytidylic acid (Poly(I:C)) and dsRNA. Ligand binding by TLR3 induces receptor dimerization which results in inducing NF-kappaB activation (via TRIF-linked RIP1/TLR3 interactions) and cytokine production. TLR3 has been shown to interact with a number of proteins including MYD88, TRAF6, TRIAD3, MAP3K7, and TAB2.