TPST1, also known as protein-tyrosine sulfotransferase 1, is the enzyme that catalyzes the sulfation reaction of protein tyrosines, a post-translational modification of proteins. It utilizes 3'-Phosphoadenosine-5'-phosphosulfate (PAPS) as the sulfonate donor and binds proteins with target tyrosine residues to eventually form the tyrosine O-sulfate ester group and the desulfonated 3'-phosphoadenosine-5'-phosphate (PAP). Recombinant human TPST1, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.