Lipopolysaccharide
class of molecules found in the outer membrane of Gram-negative bacteria
Lipopolysaccharides (LPS), also known as lipoglycans, are large molecules made of a lipid and a polysaccharide joined by a covalent bond.
![](http://up.wiki.x.io/wikipedia/commons/thumb/7/70/LPS.svg/200px-LPS.svg.png)
They occur in the outer membrane of Gram-negative bacteria, and act as triggers for the innate immune system. Their presence is sensed by toll-like receptors on dendritic cells. This causes a strong immune response in animals.