Binding of urinary protein C inhibitor to cultured human epithelial kidney tumor cells (TCL-598) : the role of glycosaminoglycans present on the luminal cell surface

摘要: Abstract Binding of urinary protein C inhibitor (PCI) to cultured human epithelial kidney tumor cells (TCL-598) was studied. dose-dependent, time-dependent, and saturable. Heparin interfered in a dose-dependent way with PCI binding TCL-598 as did heparan sulfate lesser degree also dermatan sulfate. Pretreatment protamine inhibited subsequent manner > 100 micrograms/ml reduced < 10% the control. 125I-PCI specific, bound recovered from by heparin treatment or detached together intact EDTA treatment, migrated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis same mobility (M(r) = 57,000) unbound 125I-PCI. Furthermore, cell-bound functionally active judged its ability inhibit amidolytic activity urokinase, inhibitory stimulated approximately 3-4-fold compared fluid-phase PCI. Immunogold electron microscopy revealed that PCI-antigen presented luminal side exclusively surface native well prefixed cells. This abolished presence (50 micrograms/ml) after pretreatment either (400 heparinase III (0.5 unit/ml). A slight decrease seen chondroitinase ABC AC. In contrast, extracellular matrices decreased 70% matrices, whereas both AC only matrix-bound 95%. These data suggest sulfate-containing proteoglycans are predominantly involved TCL-598, while proteoglycans, overall predominant PCI-binding TCL extracts, responsible for matrix. Heparan sulfate, however, exposed an environment containing under physiological conditions, might localize modulate target enzyme specificity vivo.