Heparanase (HPA)

Heparanase is an endo-β-D-glucuronidase that catalyzes the hydrolytic cleavage of the β-1,4-glycosidic bond between a D-glucuronate and a D-glucosamine in heparan sulfate. The physiological role of heparanase is simply to degrade heparan sulfate but this activity can take many turns.The protein is originally synthesised in an inactive 65 kDa proheparanase form in the golgi apparatus and transferred to late endosomes/lysosomes for transport to the cell-surface. In the lysosome it is proteolytically processed into its active form. The 8 kDa and 50 kDa fragments form a heterodimer and it is this heterodimer that constitutes the active heparanase molecule. The linker protein is so called because prior to its excision it physically links the 8 kDa and 50 kDa proheparanase fragments.