Chondroitin sulfate (CS) E is the natural ligand for pleiotrophin (PTN) in the central nervous system (CNS) of the embryo. Some structures of PTN in solution have been solved. but no precise location of the binding site has been reported yet. Using 15N-labelled PTN and HSQC NMR experiments. https://www.roneverhart.com/Apple-11-inch-iPad-Pro-Wi-Fi-64GB-Space-Gray-2018-release/