Final answer:
TLR4 recognizes lipopolysaccharides (LPS) and requires accessory molecules like MD-2 and CD14 to bind LPS effectively, triggering an immune response.
Step-by-step explanation:
TLR4, or Toll-like receptor 4, is a type of protein found on the cell membrane of immune cells. These receptors are part of the innate immune system and play a critical role in recognizing and responding to pathogens. TLR4 specifically recognizes lipopolysaccharides (LPS), which are complex molecules found on the outer membrane of Gram-negative bacteria.
To effectively bind to LPS, TLR4 requires the presence of accessory molecules. One such molecule is called MD-2, which associates with TLR4 and is necessary for the recognition of LPS. Another protein that is often involved in this process is CD14, which can transfer LPS to the TLR4-MD-2 complex, enhancing the immune response.
Therefore, TLR4 can only bind to LPS when it is in the correct configuration with its accessory molecules, enabling it to detect the presence of harmful bacteria and trigger an immune response.