Fig. 5. Ability of chimeric and deleted receptors to translocate FGF-1. (A) Schematic overview of the FGFR mutants. Red indicates FGFR1-derived sequences, blue indicates FGFR2 and yellow indicates FGFR4. Deletions are indicated by a broken line. (B-E) COS-1 cells were transfected with FGFR-constructs as indicated. The cells were labeled with [33P]phosphate and incubated with FGF-1 and heparin for 6 hours. FGF-1 was then extracted from the cell lysates and analyzed as in Fig. 2. Upper panels show phosphorylated FGF-1 detected by autoradiography and the lower panels show the total of endocytosed FGF-1, detected by anti-FGF-1.