Pleiotrophin (PTN) is a secreted, strongly heparinbinding, developmentally regulated cytokine. PTN is a highlyconserved protein , Human, mouse, rat, canine, porcine, equine and bovine PTN share 98% aa sequenceidentity or greater. PTN and midkine share 50% amino acid (aa) sequence identity, share some functions, andconstitute a family. During development, PTN is involved in development of brain, bone, and organsundergoing branching morphogenesis. PTN causes PTPRB dimerization and inactivates its phosphatase activity,which allows increased tyrosine phosphorylation of its substrates. Increased expression of PTN is correlatedwith neuronal development or stresses such as brain ischemia and Parkinsons disease.
