Figure S1. Cell surface levels of EGFP-CDMPR is not altered by silencing of retrograde machinery candidates.

HeLa cells stably expressing EGFP-CDMPR were transiently transfected with non-targeting siRNA (Control-kd) or siRNAs targeting TIP47, Rab9a, Vps26, μ1A, epsinR, GGA1–3, AP-2α, or clathrin CHC17. 3 d after transfection, cells were incubated with 2 μg/ml VHH-2xTS in PBS at 4°C for 1 h to label the surface fraction of EGFP-CDMPR. Subsequently, cells were washed and lysed, and endogenous protein levels were analyzed by immunoblotting with antibodies against the indicated proteins (VHH-2xTS was detected with anti-His6). Only knockdown of CHC17 influenced surface levels of EGFP-CDMPR (monitored by bound nanobody). Total EGFP-CDMPR remained unaffected in all knockdowns.