Cellular uptake of rPrP occurs by endocytosis.

<p>(A) Reporter cells containing <i>lox</i>P-STOP-<i>lox</i>P GFP reporter gene were treated with indicated proteins for 1 hr, incubated overnight, then assayed for GFP expression by flow cytometry (±SD). (B) Reporter cells were treated with rPrP (23–90)-Cre in the presence of heparin or chondroitin sulfate B, washed, incubated overnight, then assayed for GFP-positive cells by flow cytometry (±SD). (C) N2a cells were transfected with Cav1α-GFP expression plasmid, followed 48 hr later by treatment with rPrP-546 (red) and live cell confocal microscopy. Scale bar = 5 µm. (D) N2a cells co-transfected with pDyn^K44A-HA dominant-negative and pZ/EG <i>lox</i>P-stop-<i>lox</i>P GFP reporter plasmids were treated with rPrP (23–90)-Cre protein. Scale bar = 25 µm. (E) N2a cells co-transfected with pDyn^K44A-HA and pEGFP (constitutive GFP expression) plasmids (10∶1) were incubated with fluorescent transferrin-TMR (red) as a positive control for Dyn^K44A activity. Arrows indicate Dyn^K44A/EGFP transfected cells. Scale bar = 20 µm.