Intracellular disposition of arabinogalactan and asialofetuin in HepG2 cells

The binding and uptake of arabinogalactan and asialofetuin in HepG2 cells was kinetically characterized using I-125-labeled ligands. The number of binding sites (n) and the association constant (K-a) of arabinogalactan was 1.9 x 10(5) +/- 1.2 x 10(5) sites/cell and 5.0 x 10(6) +/- 3.9 x 10(6) M-1, respectively, whereas the n and K-a of asialofetuin was 2.7 x 10(5) +/- 1.1 x 10(5) sites/cell and 1.1 x 10(7) +/- 0.7 x 10(7) M-1, respectively. These results suggest that the binding capacity of HepG2 cells for arabinogalactan is lower than that for asialofetuin. Moreover, the amount of arabinogalactan uptake by HepG2 cells was lower than that of asialofetuin. Thus, asialofetuin was preferentially bound and internalized by hepatoma cells compared to arabinogalactan.