Tristetraproline (TTP) binds RNAs that contain AU-rich elements and recruits enzymes that degrade RNA. TTP interacts with the exosome (3' to 5' exonuclease), XRN1 (5' to 3' exonuclease), and the decapping enzymes DCP1 and DCP2a.
The activity of TTP is regulated by phosphorylation. MK2 phosphorylates TTP, which then binds 14-3-3.The interaction with 14-3-3 prevents phosphorylated TTP from entering stress granules and stabilizes mRNA bound by phosphorylated TTP. Tristetraproline is known to bind AU-rich elements in the following mRNAs: Tumor necrosis factor alpha (TNFA), Granulocyte-macrophage colony stimulating factor (CSF2, GM-CSF), Interleukin-2 (IL-2), and Proto-oncogene C-FOS (FOS, c-fos). Mice deficient in TTP exhibit arthritis, weight loss, skin lesions, autoimmunity, and myeloid hyperplasia.