Isolation of two new proteins from bovine colostrum which stimulate epidermal growth factor-dependent colony formation of NRK-49F cells.
Defatted bovine colostrum and decaseinated whey contain biological activity similar to that of TGF-beta in that they stimulate the anchorage-independent growth of NRK-49F cells in the presence of EGF. Two new proteins with such activity, termed BC-1 and BC-2, were isolated from decaseinated colostrum by a sequence of DEAE-Sephacel chromatography, Sephadex G-100 gel filtration in 1 M acetic acid, Sephadex G-50 re-gelfiltration in 8 M urea-1 M acetic acid and reverse-phase FPLCs. The two proteins showed distinctly different molecular weight from that of TGF-beta 1. BC-1 was a small Mr peptide of 8.5 kD. BC-2 had molecular mass of 46 kD, which yielded peptides of 46,40, and 6 kD on reduction. In contrast to TGF-beta, both proteins did not lose their biological activity on reduction. Both BC-1 and BC-2 suppress DNA synthesis in concanavalin A-stimulated thymocytes. These results suggest that BC-1 and BC-2 belong to a new class of mitogen/inhibitors, though their biological activities resemble those of TGF-beta.
Department of Molecular Immunology, Faculty of Medicine, Kanazawa University, Ishikawa-ken, Japan.
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Tokuyama
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Tokuyama
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Migita
D000818:Animals; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003126:Colostrum / Q000737:chemistry*; D003208:Concanavalin A / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis; D004815:Epidermal Growth Factor / Q000494:pharmacology; D006133:Growth Substances / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D008213:Lymphocyte Activation; D008970:Molecular Weight; D013601:T-Lymphocytes / Q000378:metabolism; D015291:Transforming Growth Factors / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology
D006133:Growth Substances; D003208:Concanavalin A; D004815:Epidermal Growth Factor; D015291:Transforming Growth Factors; D004247:DNA