# Pattern Recognition Receptors --- **Pattern recognition receptors** or **PRRs** are receptors that are (primarily) found on the membranes and in the cytoplasm of [[innate immune system#Innate Immune Cells|innate immune cells]] that specifically recoginize molecules associated with pathogens. Some examples of what a PRR might recognize are: - [[flagella|flagellin]] (the protein that flagella are comprised of) - [[Gram negative bacteria#Lipopolysaccharides|lipoppolysaccharides]] - [[Gram positive bacteria#Teichoic Acids|teichoic acid]] - [[Gram negative bacteria#Lipoproteins|lipoprotein]] - [[virus#Nucleic Acids|viral RNA]] ## Types There are three major types of PRRs, toll-like receptors, NOD-like receptors, and RIG-like receptors. ### Toll-like Receptors **[[toll-like receptor|Toll-like receptors]]** are found on the surface of [[macrophages]], [[B-cells]], [[dendritic cells]], and some other cells. There are many different types and they each recognized a different type of molecule that is generally associated with foreign cells, like a flagellum. ### NOD-like Receptors **NOD-like receptors** are found in the cytoplasm of [[macrophages]], and when activated can cause the macrophage to release messenger molecueles to trigger [[inflammation]]. ### RIG-like Receptors **RIG-like Receptors** are found in the cytoplasm of [[innate immune system#innate immune cells|innate immune cells]] that bind specifically to molecular patterns found on [[virus|viruses]]. ___