Serotonylation
Serotonylation is a receptor independent signaling mechanism by which serotonin activates intracellular processes by creating long lasting covalent bonds upon proteins.[1] It occurs through the modification of proteins by the attachment of serotonin on their glutamine residues. This happens through the enzyme transglutaminase and the creation of glutamyl-amide bonds. This process occurs following serotonin transportation into the cell rather on plasma membranes as with the brief interactions that serotonin has when it activates 5-HT receptors.