CNPY4 belongs to the canopy family. CNPY4 interacts with toll-like receptor 4 (TLR4) and plays a role in the regulation of the cell surface expression of TLR4. Toll-like receptors (TLRs) recognize microbial products and induce immune responses. Lipopolysaccharide is recognized by the receptor complex consisting of TLR4 and MD-2. As CNPY4, PRAT4B also regulates cell surface expression of TLR4. PRAT4B has a signal peptide followed by a mature peptide. It is associated with the hypoglycosylated, immature form of TLR4 but not with MD-2 or TLR2.