Evidence that the axolemmal mitogen for cultured Schwann cells is a positively charged, heparan sulfate proteoglycan-bound, heparin-displaceable molecule.

Treatment of axolemma with pH 9 buffer results in a pellet enriched two-fold in the mitogen for cultured Schwann cells. Heparitinase treatment releases 8% of the mitogen into solution, while heparin selectively solubilizes the mitogen, resulting in an extract which has a specific mitogenic activity approximately 2.5 times greater than the mitogenicity of the starting axolemma membrane. These data support a model in which the axolemmal mitogen is a positively charged molecule associated with negatively charged sulfated proteoglycans.