Abstract
Trans-endocytosis is a force dependent process during which surface molecules expressed on one cell but bound to their receptors on another cell are displaced and internalized by the cell expressing the receptors. The efficiency of trans-endocytosis is associated with the capacity of force generation of the cell. Here we present three different methods to measure the forces generated during trans-endocytosis using tension gauge tether (TGT), micropillar arrays, and microfluidic devices. The TGT method detects forces generated at the single-molecule (nm) scale and the other two methods detect forces with the resolution at the micron scale. Trans-endocytic forces transmitted via the receptors at dorsal side of the cell can be determined using the TGT and the microfluidic-based methods, while forces transmitted at the ventral side can be determined using the micropillar-based method.