title: Investigations of the possible role of proteases in altering surface proteins of virally transformed hamster fibroblasts.
abstract: Virally transformed fibroblasts have on their surfaces zero or reduced amounts of a large external transformation-sensitive (LETS) glycoprotein. This protein is extremely sensitive to proteolysis. When prelabeled normal fibroblasts are cocultivated with transformed cells, the LETS glycoprotein of the normal cells shows an increased rate of turnover. Experiments are described which investigate the possibility that this phenomenon and the absence of LETS glycoprotein are due to proteolysis by the transformed cells. In particular, the role of plasminogen activation is examined by the use of protease inhibitors and plasminogen-depleted serum. It is concluded that activation of plasminogen is not required for the disappearance of the LETS glycoprotein although the involvement of other proteases cannot be ruled out. The role of proteases in affecting cell growth and behavior is discussed.
mesh_terms: D000614:Aminocaproates / Q000494:pharmacology; D001769:Blood; D002455:Cell Division; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D005342:Fibrinolysis / Q000187:drug effects; D006023:Glycoproteins / Q000378:metabolism*; D010059:Ovomucin / Q000494:pharmacology; D010447:Peptide Hydrolases / Q000378:metabolism*; D010958:Plasminogen / Q000494:pharmacology; D014106:Tosylarginine Methyl Ester / Q000494:pharmacology; D014107:Tosyllysine Chloromethyl Ketone / Q000494:pharmacology; D014108:Tosylphenylalanyl Chloromethyl Ketone / Q000494:pharmacology; D014361:Trypsin Inhibitors / Q000494:pharmacology
chemical_list: D000614:Aminocaproates; D006023:Glycoproteins; D014361:Trypsin Inhibitors; D014107:Tosyllysine Chloromethyl Ketone; D010059:Ovomucin; D014108:Tosylphenylalanyl Chloromethyl Ketone; D010958:Plasminogen; D014106:Tosylarginine Methyl Ester; D010447:Peptide Hydrolases