Interaction of nerve growth factor with surface membranes: biological competence of insolubilized nerve growth factor

Nerve growth factor was insolubilized by covalent attachment to Sepharose beads. Nerve growth factor-Sepharose was biologically active in both the neurite outgrowth assay for nerve growth factor and in preserving responsive neurons in vitro. Modification of the bioassay to detect solubilized activity of nerve growth factor and histological examination of ganglia treated with nerve growth factor-Sepharose revealed that nerve growth factor-Sepharose prepared by reaction in 6 M guanidine hydrochloride released negligible amounts of solubilized nerve growth factor activity. These observations extend the previously noted correlations on the structure and function of nerve growth factor and insulin to include the primary action of these two proteins. Thus nerve growth factor, like insulin, appears to express its biological activity by first binding to a receptor on the surface membrane of responsive cells.