Fig. 2.

Effect of mutations in PAPP-A on IGFBP-4 (A) and IGFBP-5 (B) proteolysis. Conditioned medium from AoSMCs transfected with plasmids encoding WT and mutated PAPP-A was incubated with ¹²⁵I-labeled IGFBP. Intact and fragmented IGFBPs are indicated by arrows. IGFBP-4 fragments run as a single band because PAPP-A-mediated IGFBP-4 proteolysis is IGF dependent. −/+ indicates incubation without and with IGF-II. For IGFBP-5 proteolysis, −/+ indicates without or with incubation. IGFBP-5 is O-glycosylated, giving rise to the cleavage products of different sizes. Conditioned medium from transfection experiments using three individual clones of each mutant was used for analysis. Molecular mass markers (in kilodaltons) are indicated on the left. Frag, fragmented.