Fig. 6. Model of Suramin effects on PrP biogenesis and propagation of PrPSc. The biosynthesis of PrPc in the exocytotic pathway and its recycling and degradation in the endocytotic pathway are depicted (–Sur; PrPc shown by shaded circles). The putative subcellular compartment of conversion of PrPc into PrPSc in the early endocytotic pathway is marked (rafts or caveolae; Taraboulos et al., 1995). PrPSc, which is not efficiently degraded in lysosomes, is indicated by black boxes. The induction of detergent-insoluble PrP aggregates by Suramin in post-ER compartments and the direct re-routing to acidic vesicles are indicated (+Sur; red arrow; PrP depicted by red boxes). As a result of this re-routing, the plasma membrane localization and the putative compartment of prion conversion are bypassed.