Purification and initial characterization of a type beta transforming growth factor from human placenta.
A polypeptide transforming growth factor (TGF) that induces anchorage-dependent rat kidney fibroblasts to grow in soft agar has been isolated from human placenta and purified to homogeneity. This polypeptide is classified as a type beta TGF because it does not compete with epidermal growth factor (EGF) for membrane receptor sites but does require EGF for induction of anchorage-independent growth of indicator cells. Purification of this peptide was achieved by acid/ethanol extraction of the placenta, followed by gel filtration, cation exchange, and HPLC of the acid-soluble proteins. Homogeneity of the TGF-beta from the final column was shown by its constant specific activity and amino acid composition across the peak of soft agar colony-forming activity and by its migration as a single band at Mr 23,000-25,000 on NaDodSO4/polyacrylamide gel electrophoresis. Under reducing conditions, the protein migrated on a gel as a single band at Mr 13,000. The purified placental TGF-beta caused half-maximal growth stimulation of indicator cells in soft agar at 64-72 pg/ml (3 pM) in the presence of EGF at 2 ng/ml (0.34 nM).
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001681:Biological Assay; D002460:Cell Line; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005260:Female; D006801:Humans; D007668:Kidney / Q000187:drug effects; D008970:Molecular Weight; D010455:Peptides / Q000302:isolation & purification*; D010920:Placenta / Q000032:analysis*; D011247:Pregnancy; D051381:Rats; D015291:Transforming Growth Factors
D000596:Amino Acids; D010455:Peptides; D004815:Epidermal Growth Factor; D015291:Transforming Growth Factors