Association of productive (A) and non-productive (B) particles with AP-2 clathrin adaptor, dynamin, and Rab5.

“Productive particles” are those that bind and uncoat as in Figure 3; “non-productive particles”, those that fail to uncoat within 30 mins of binding. Of 62 productive particles followed in cells transfected with σ2-eGFP (A, left), 50 did not colocalize with σ2 at any time, while 12 colocalized with σ2 at an early time point. Likewise, of 62 productive particles followed in Rab5-eGFP transfected cells (A, right), only 11 appeared to colocalize with Rab5, while of 166 non-productive particles (B, right), a substantial majority ended up in Rab5 endosomes. Cells stably transfected with σ2-eGFP or Rab5-eGFP or transiently transfected with dynamin-eGFP.