Heparin-Binding Proteins in the Rat Brain

Using a histochemical technique, we found that in rat embryos heparin-binding sites are localized within ventricular regions of the neural tube. The highest intensity of the heparin-binding activity was observed in the membranes of migrating nerve cells. Heparin-binding membrane-associated proteins were isolated and purified from the brains of newborn rats; molecular masses of two such proteins were measured (19 and 28 kdalton). The level of affinity for binding of heparan sulfate to the purified proteins was characterized by equilibrium constants of 1.7 · 10^-3 and 6.7 · 10^-3. Binding of heparan sulfate to the above proteins was more intensive at low ion force and pH values within the 3.0 to 4.0 range and about 6.0.