Fig. 6. Visualization of lipoprotein distribution after receptor-mediated endocytosis. CHO(LpR) (A), CHO(LpR_1-790LDLR_791-839) (B), ldlA(LpR_1-342LDLR_293-839) (C), ldlA(LDLR) (D), ldlA(LDLR_1-292LpR_343-850) (E), ldlA(LDLR_H562N) (F) and ldlA(LDLR_H562Y) transfectants (G) were preincubated for 15 minutes with OG-Lp (A-C) or OG-LDL (D-G), followed by a 60-minute chase in growth medium without ligand. After fixation, the receptors were detected with IF using anti-LpR antibody 2189/90 (A-C) or anti-LDLR antibody C7 (D-G). Fluorescence microscopy reveals that CHO(LpR) (A) and CHO(LpR_1-790LDLR_791-839) (B) transfectants have become depleted of lipoprotein (left), whereas the ligand remains visible in the other cell lines (C-G, grey). In contrast to wt LpR (A), LpR_1-790LDLR_791-839 (B) and wt LDLR (D), the other receptors are scattered throughout the cell and do not prominently converge in the ERC (middle, grey). Although they are more diffuse, the intracellular distributions of LpR_1-342LDLR_293-839 (C), LDLR_1-292LpR_343-850 (E), LDLR_H562N (F) and LDLR_H562Y (G) coincide with that of the internalized ligand (right – lipoprotein, green; receptor, red; colocalization, yellow). Scale bar, 10 µm (G, right).