Endoglycosidase that cleaves heparan sulfate proteoglycans (HSPGs) into heparan sulfate side chains and core proteoglycans. Participates in extracellular matrix (ECM) degradation and remodeling. Selectively cleaves the linkage between a glucuronic acid unit and an N-sulfo glucosamine unit carrying either a 3-O-sulfo or a 6-O-sulfo group. Can also cleave the linkage between a glucuronic acid unit and an N-sulfo glucosamine unit carrying a 2-O-sulfo group, but not linkages between a glucuronic acid unit and a 2-O-sulfated iduronic acid moiety. It is essentially inactive at neutral pH but becomes active under acidic conditions such as during tumor invasion and in inflammatory processes. Facilitates cell migration associated with metastasis, wound healing and inflammation. Enhances shedding of syndecans, and increases endothelial invasion and angiogenesis in myelomas. Acts as procoagulant by increasing the generation of activation factor X in the presence of tissue factor and activation factor VII. Increases cell adhesion to the extracellular matrix (ECM), independent of its enzymatic activity. Induces AKT1/PKB phosphorylation via lipid rafts increasing cell mobility and invasion. Heparin increases this AKT1/PKB activation. Regulates osteogenesis. Enhances angiogenesis through up-regulation of SRC-mediated activation of VEGF. Implicated in hair follicle inner root sheath differentiation and hair homeostasis. endohydrolysis of (1->4)-beta-D-glycosidic bonds of heparan sulfate chains in heparan sulfate proteoglycan. Inhibited by EDTA, laminarin sulfate and, to a lower extent, by heparin and sulfamin and activated by calcium and magnesium. kcat is 0.53 sec(-1) for M09 S05a. Optimum pH is 4-6. Heterodimer; heterodimer formation between the 8 kDa and the 50 kDa subunits is required for enzyme activity. Interacts with TF; the interaction, inhibited by heparin, enhances the generation of activated factor X and activates coagulation. Interacts with HRG; the interaction is enhanced at acidic pH, partially inhibits binding of HPSE to cell surface receptors and modulates its enzymatic activity. Interacts with SDC1; the interaction enhances the shedding of SDC1. Interacts with HPSE2. Proheparanase is secreted via vesicles of the Golgi. Interacts with cell membrane heparan sulfate proteoglycans (HSPGs). Endocytosed and accumulates in endosomes. Transferred to lysosomes where it is proteolytically cleaved to produce the active enzyme. Under certain stimuli, transferred to the cell surface. Associates with lipid rafts. Colocalizes with SDC1 in endosomal/lysosomal vesicles. Accumulates in perinuclear lysosomal vesicles. Heparin retains proheparanase in the extracellular medium (By similarity). Highly expressed in placenta and spleen and weakly expressed in lymph node, thymus, peripheral blood leukocytes, bone marrow, endothelial cells, fetal liver and tumor tissues. Also expressed in hair follicles, specifically in both Henle's and Huxley's layers of inner the root sheath (IRS) at anagen phase. Proteolytically processed. The cleavage of the 65 kDa form leads to the generation of a linker peptide, and 8 kDa and 50 kDa products. The active form, the 8/50 kDa heterodimer, is resistant to degradation. Complete removal of the linker peptide appears to be a prerequisite to the complete activation of the enzyme. N-glycosylated. Glycosylation of the 50 kDa subunit appears to be essential for its solubility. Escapes proteolytic cleavage, devoid of HS degradation activity. Belongs to the glycosyl hydrolase 79 family.