Studies on shrew (Suncus murinus) epidermal growth factor.

The shrew SMG contains a very high level of EGF. By heterologous radioreceptor assay, the EGF content was determined to be about 300 pmol/mg wet weight in the male. The content is sex dependent; in the female gland, it is only 4% of the male gland level. EGF level and EGF receptor content in other tissues showed a reciprocal distribution pattern with the parotid gland containing the second highest level of EGF and the liver containing the largest amount of EGF receptor. Shrew EGF is heat stable. It could induce early eyelid opening and incisor eruption in neonatal rat pups at a very low dose level. There is apparently no high molecular weight form of EGF in shrew tissues and body fluids. However, gel chromatography revealed that the foetus contained multiple forms of EGF. The contribution of a high EGF level to the active life in adult shrews and the exceptionally high growth rate in shrew pups are discussed.