A beta-type transforming growth factor, present in conditioned cell culture medium independent of cell transformation, may derive from serum.
An alpha-type transforming growth factor (TGF alpha) is produced at high levels by rat embryo cells transformed by the Snyder-Theilen strain of feline sarcoma virus (FeSV). Addition of 2 ng mouse epidermal growth factor (mEGF) during purification identified the presence of a second, EGF-dependent growth factor of the TGF beta type (TGF beta) in this conditioned medium. This factor had an approximate Mr of 12,000 and eluted at 37% acetonitrile during high performance liquid chromatography. This extracellular type of TGF beta activity also was present in conditioned medium of rat cells after infection with a transformation defective strain of Abelson leukemia virus, and hence expression of this growth factor activity was independent of cell transformation. Moreover, the presence of an EGF-dependent, 12,000 Mr clonogenic activity in extracts of bovine serum alone suggests serum as an origin for the B-type transforming growth factor initially observed in conditioned medium of Snyder-Theilen FeSV transformed cells. This does not, however, preclude the possibility that TGF beta is also secreted by the transformed rat embryo cells themselves.
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DR
D000818:Animals; D001769:Blood; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D002472:Cell Transformation, Viral; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media; D004622:Embryo, Mammalian; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D008970:Molecular Weight; D010455:Peptides / Q000097:blood* / Q000302:isolation & purification; D051381:Rats; D005253:Sarcoma Viruses, Feline; D015291:Transforming Growth Factors
D003470:Culture Media; D010455:Peptides; D004815:Epidermal Growth Factor; D015291:Transforming Growth Factors