TLRs or Toll-like receptors are a class of proteins that play a key role in the innate immune system. They are usually found on the cell surface of sentinel cells such as macrophages and dendritic cells, that recognize structurally conserved molecules derived from microbes.
Upon activation, TLRs recruit adaptor proteins within the cytosol of the immune cell to propagate the antigen-induced signal transduction pathway which leads to a cascade of events.
![](https://s2.save4k.ru/pic/lEg75Rb8u0Q/maxresdefault.jpg)