Two forms of murine epidermal growth factor: rapid separation by using reverse-phase HPLC.

Abstract
Epidermal growth factor (EGF) was isolated from acid extracts of C57BL6/J mouse submaxillary glands by using hydrophobic chromatography. High yields of EGF in large amounts (10 mg) can be isolated reliably from the acid extract of the glands in less than 4 h. The reverse-phase high performance liquid chromatography techniques used to purify the EGF initially yielded what appeared to be a single homogeneous EGF molecule. However, ion pairing reagents (e.g., heptafluorobutyric acid) altered the chromatographic properties, revealing 2 distinct species: EGF-.alpha. and EGF-.beta.. The apparent MW, isoelectric points and antigenic properties of EGF-.alpha. and EGF-.beta. were identical, and both forms stimulated a mitogenic response in mouse fibroblast 3T3 cells. Analysis of different preparations of purified EGF (commercial and experimental) indicated the presence of EGF-.alpha. and EGF-.beta. in constant proportion. Previous EGF binding studies must have used mixtures of 125I-labeled EGF-.alpha. and 125I-labeled EGF-.beta.. The 2 molecules appear to compete for an identical receptor on the cell surface.