Coreceptor for bacterial lipopolysaccharide. In concert with LBP, binds to monomeric lipopolysaccharide and delivers it to the LY96/TLR4 complex, thereby mediating the innate immune response to bacterial lipopolysaccharide (LPS). Acts via MyD88, TIRAP and TRAF6, leading to NF-kappa-B activation, cytokine secretion and the inflammatory response. Acts as a coreceptor for TLR2:TLR6 heterodimer in response to diacylated lipopeptides and for TLR2:TLR1 heterodimer in response to triacylated lipopeptides, these clusters trigger signaling from the cell surface and subsequently are targeted to the Golgi in a lipid-raft dependent pathway. Binds electronegative LDL (LDL(-)) and mediates the cytokine release induced by LDL(-) (By similarity). Belongs to the lipopolysaccharide (LPS) receptor, a multi-protein complex containing at least CD14, LY96 and TLR4. Interacts with LPS-bound LPB. Interacts with LPAR1. Interacts with the TLR2:TLR6 or TLR2:TLR1 heterodimers; upon interaction with ligands such as diacylated lipopeptides and triacylated lipopeptides, respectively. Interacts with MYO18A. Interacts with FSTL1. Soluble, secreted forms seem to exist. They may arise by cleavage of the GPI anchor. Detected in lung (PubMed:9300371, PubMed:8643545). Detected in brain and kidney (PubMed:9300371). Detected in trachea and bone marrow (PubMed:8643545). Up-regulated in peripheral blood monocytes exposed to bacterial lipopolysaccharide (LPS). The C-terminal leucine-rich repeat (LRR) region is required for responses to smooth LPS.