Partial purification and characterization of masking protein for beta-type transforming growth factor from rat platelets.
beta-Transforming growth factor (TGF-beta) is stored in platelets and secreted as a high molecular weight latent form associated with a carrier protein of about 440 KD. This carrier protein could be separated from TGF-beta in 1 N acetic acid and could again mask the activity of TGF-beta under neutral conditions. Therefore, it was named the masking protein of TGF-beta. The masking protein was separated from TGF-beta by gel filtration on a Sephacryl S-300 column or by anion-exchanger FPLC on a Mono Q column in the presence of 6 M urea. Partially purified masking protein from rat platelets neutralized the activity of TGF-beta dose-dependently and was effective at 0.3 microgram/ml. This masking protein could also mask the activity of human TGF-beta, suggesting that it was not species specific. The masking protein was a heat- and acid-stable protein, but was inactivated by treatment with dithiothreitol. The Physiological role of the masking protein in the mechanisms of wound healing and liver regeneration is discussed.
D000818:Animals; D001792:Blood Platelets / Q000032:analysis*; D002352:Carrier Proteins / Q000302:isolation & purification* / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D004247:DNA / Q000096:biosynthesis; D004229:Dithiothreitol / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000494:pharmacology; D053779:Latent TGF-beta Binding Proteins; D008099:Liver / Q000166:cytology; D008970:Molecular Weight; D010455:Peptides / Q000037:antagonists & inhibitors*; D051381:Rats; D013045:Species Specificity; D016212:Transforming Growth Factor beta; D015291:Transforming Growth Factors
D002352:Carrier Proteins; D007328:Insulin; D053779:Latent TGF-beta Binding Proteins; D010455:Peptides; D016212:Transforming Growth Factor beta; D004815:Epidermal Growth Factor; D015291:Transforming Growth Factors; D004247:DNA; D004229:Dithiothreitol