Conversion of a high molecular weight latent beta-TGF from chicken embryo fibroblasts into a low molecular weight active beta-TGF under acidic conditions.
A latent beta-TGF activity is spontaneously released into serum-free culture medium by chicken embryo fibroblasts. Anchorage-independent growth activity measured on NRK-49F indicator cells, of this latent beta-TGF can be revealed by four different treatments: acidification, alkalinisation, exposure to urea, and heating to 100 degrees C for 3 minutes. This lact activating treatment indicates that latent beta-TGF activation in vitro is non-enzymatic. Active beta-TGF exists in a low molecular weight form 16 Kd (apparent) in 1M acetic acid, which elutes on reverse phase (FPLC) between 33-35% acetonitrile. Under neutral conditions only a high molecular weight form excluded on Biogel P60 is observed. This form is poorly active on NRK-49F for anchorage independent growth but can be fully activated by prior acidification. Rechromatography of the latent beta-TGF-containing fractions under acidic conditions converts the high molecular weight form to an apparent 16 Kd active form. We suggest that the high molecular weight form may correspond to a complex of a beta-TGF associated with a carrier or binding protein.
D000818:Animals; D001711:Biotransformation; D002642:Chick Embryo; D002999:Clone Cells; D003470:Culture Media; D005347:Fibroblasts / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000378:metabolism; D008970:Molecular Weight; D010455:Peptides / Q000378:metabolism*; D051381:Rats; D015291:Transforming Growth Factors
D003470:Culture Media; D010455:Peptides; D015291:Transforming Growth Factors