Fig. 9.

Strumpellin depletion or mutation does not affect the uptake or recycling of the transferrin receptor. HeLa cells depleted of either strumpellin or clathrin heavy chain (as a positive control) were incubated with fluorescent transferrin and used in either uptake (A) or recycling (B) assays. The amount of internalised transferrin present after 20 min in each assay was measured by flow cytometry. To examine the steady-state distribution of the transferrin receptor, mock-transfected cells or cells transfected with siRNA against strumpellin were labelled for TfnR (C). Cells transfected with wild-type or disease mutant strumpellin, or with an empty vector, were also used in uptake (D) and recycling (E) assays, with depletion of the clathrin heavy chain used as a positive control. Error bars = S.E.M, n = 3 experiments in (A), (B), (D) and (E).