Toll-like receptor 4

Toll-like receptor 4 is a protein that in humans is encoded by the TLR4 gene. TLR 4 is a toll-like receptor which is responsible for activating the innate immune system. It is most well-known for recognizing lipopolysaccharide (LPS), a component of Gram-negative bacteria, but its ligands also include several viral proteins, polysaccharide, and a variety of endogenous proteins such as low-density lipoprotein, beta-defensins, and heat shock protein.