Figure 9.

PC5A/TIMP-2 complex binds HSPGs at the cell surface and the CRD enhances processing of proEL by PC5A. (A) Displacement of cell surface PC5A by exogenous heparin or heparinase-I as revealed by confocal microscopy with Ab:V5, in COS-1 cells transfected with pIRES-EGFP recombinant of FL-PC5A. The green EGFP fluorescence indicates nuclei of transfected cells. Bar, 10 μm. (B) HEK293 cells stably expressing human proEL-myc (see cartoon, left) were transiently transfected with indicated PC-constructs in pIRES-EGFP, where Vector represents an empty control pIRES-EGFP vector. The cells were pulse labeled with [³⁵S]Cys/Met for 2 h and then chased for 4 h. Cell lysates were immunoprecipitated with the anti-myc antibody and analyzed by SDS-PAGE on 8% Tricine gels. The migration positions of proEL and its C-terminal cleavage product (CT-EL) are emphasized together with those of the molecular mass standards.