Subunit structure of a high-molecular-weight form of the nerve growth factor from mouse submaxillary gland.

Abstract

An NGF [nerve growth factor] protein has been purified 40-fold from homogenates of adult male mouse salivary glands. The NGF activity is associated with a single protein component comprising over 95% of the total protein of the fraction. It represents 2% of the soluble protein of the gland and 80% of the expressed activity of the gland homogenate. The molecular weight of this NGF species is 140,000. It dissociates reversibly at acid and alkaline pH into subunits of 30,000 molecular weight, the dissociation being accompanied by a reversible fourfold decrease in activity. Three types of NGF subunits can be separated by chromatography at acid pH, only one of them having biological activity and this at about one quarter the level of the original NGF. The three isolated subunits recombine at neutral pH to reform the original highly active NGF molecule.