MD2

Toll-like receptor 4 (TLR4) belongs to the family of Toll-like receptors (TLR), and plays a main role in pathogen recognition and innate immunity system activation. The TLR family members are highly conserved proteins that all contain a high degree of structural and functional homology in organisms from Drosophila all the way up to humans. TLRs regulate the cellular cytokine production required for efficient innate immunity development through their recognition of pathogen-associated molecular patterns (PAMPs) expressed across a wide range of ligands, including infectious agents.

CD14 is a well-characterized cell-activating receptor for lipopolysaccharide-binding protein (LBP) and peptidoglycan. It is an important modulator for lipopolysaccharide (LPS)-dependent signaling and is a component of the multi-protein complex containing also containing MD2 and toll-like receptor 4 (TLR4). CD14 is an important component of the innate immune response preferentially expressed on mature cells of monocyte lineage. The CD14 protein contains eleven leucine-rich repeats (LRRs).