Some properties of human epidermal growth factor (hEGF)-like immunoreactive material originating from platelets during blood coagulation.

During blood coagulation, a considerable amount of human epidermal growth factor (hEGF)-like immunoreactive material (designated as platelet hEGF-LI) was liberated from platelets. The molecular nature of the platelet hEGF-LI was examined. The molecular weight of platelet hEGF-LI estimated by gel filtration was approximately 60,000-70,000. On chromatofocusing chromatography, platelet hEGF-LI was eluted mainly at pH 4.75 as a sharp peak with a minor peak at 4.30, like urine EGF. By treatment with 2-mercaptoethanol, the factor was converted into a material with molecular weight of 35,000-40,000. These results suggest that the majority of hEGF-LI in platelets may exist either in a covalently bound-form with some protein(s) in platelets or as a dimer intermolecularly cross-linked by an S-S linkage. Details of the biological properties and the physiological significance of the platelet hEGF-LI remain to be clarified.