Toll-Like Receptor 9
Toll receptors are transmembrane proteins that are evolutionarily conserved. These receptors were first recognized in Drosophila, as an essential molecule for embryogenic patterning (Anderson 2000).
Activation of these receptors in Drosophila initiates an intracellular kinase cascade that produces a translocation of transcription factors from cytoplasm to nucleus. These factors activate a variety of inflammatory mediators and cytokines, initiating an immune response (Imler and Hoffmann 2000).
Considering these facts, some researchers began a search for toll-related proteins in humans. In 1997, they identified the first human homologue, initially termed “human toll” and subsequently termed TLR4 (Medzhitov et al. 1997). After this, more toll-like receptors were discovered, as TLR1, TLR2, TLR3, TLR5, and TLR6.
In 2000, Du et al. examined the human genomic sequence database in an effort to identify novel TLRs (Du et al. 2000). He found more three...