Merlin-DCAF1 interaction in vitro and in vivo. (A) Glutathione bead-conjugated GST-merlin constructs were incubated with lysates from DCAF1 transfected COS-7 cells, and bound proteins were detected with antibody against DCAF1 (upper panel) and merlin with GST Ab (lower panel). Merlin 1–314 binds DCAF1, whereas 1–100, 314–477, and 492–595 merlin show no binding. Mutation of S10 does not affect the DCAF1 binding affinity of merlin fragments. (B) DCAF1 was immunoprecipitated from merlin and DCAF1-cotransfected COS-7 cell lysates, and merlin was detected with KF10 Ab (upper panel). Equal amounts of proteins were expressed as shown in lysates (lower panels), and untransfected cells (-) were used as control. S518D merlin interacts strongly, whereas S10A + S518D merlin shows reduced binding affinity to DCAF1.