Fig 4.

Endogenous CD44 binds to ligand-binding cluster IV of LRP-1. (A) Schematic representation of native LRP-1 and minireceptors derived from LRP-1 carrying extracellular binding domain IV (mini LRP-IV), extracellular binding-domain II (mini LRP-II) or no-ligand-binding cluster (SPCT). (B) FTC-133 cells were transiently transfected with HA-tagged SPCT (SPCT), HA-tagged mini LRP-II (D2), or HA-tagged mini LRP-IV (D4). Nontransfected cells served as a control (Ctrl). After 24 h of transfection, biotinylation of cell surface proteins was performed, followed by an immunoprecipitation (IP) assay with an anti-HA tag antibody. Then, immunoblot (IB) analysis was conducted using both anti-HA tag and anti-CD44 antibodies (A020). Bands revealed by the anti-HA tag antibody correspond to the expected molecular masses of SPCT (106 kDa; arrowhead), mini LRP-II (153 kDa; star), and mini LRP-IV (164 kDa; double star).