Inhibition of binding of basic fibroblast growth factor to low and high affinity receptors by carrageenans

Abstract

The effect of carrageenans, a family of polysulphated polysaccharides, on the binding of basic fibroblast growth factor (bFGF) to low affinity (heparin-like) receptors and high affinity receptors on baby hamster kidney cells was investigated. κ-, ι- and λ-carrageenans all inhibited binding of bFGF to both types of receptors with ι-carrageenan being the most potent inhibitor ( ic 50 values of approx. 0.7 and 4 μg/mL for inhibition of binding to low and high affinity receptors respectively). Heparin reduced the inhibition of bFGF binding to high affinity receptors caused by ι-carrageenan. Heparin and ι-carrageenan were comparable in their activities at displacing pre-bound bFGF from both low affinity receptors and high affinity receptors. These results indicate that ι-carrageenan binds to the heparin-binding domain on bFGF and that this may be sufficient to reduce the ability of bFGF to bind to high affinity receptors.