Purification and partial characterization of two types of growth-inhibitory protein latently present in rabbit serum.
Normal rabbit serum contained two kinds of growth-inhibitory protein, GI-I and GI-II, in latent forms. These latent inhibitors were activated by incubation at 37 degrees C for 12 h, and their activation was lowered by inhibitors for serine, cysteine and metalloproteinases. Both growth inhibitors were highly purified in active forms by successive column chromatographies. GI-I showed a major protein band with an Mr of 18,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, while GI-II showed a major protein band with an Mr of 36,000. GI-I and GI-II half-inhibited the growth of rat tumorigenic cell line (RSV-BRL) at concentrations of 0.5 ng/ml and 10 ng/ml, excess concentrations. Of the 15 cell lines tested, GI-I specifically inhibited the growth of rodent and lagomorph cells, whereas GI-II nonspecifically inhibited the growth of all cell lines tested. Specificities for cell type and malignancy were not observed with either inhibitor. These growth inhibitors were stable to a reducing reagent and proteinase inhibitors, but labile to urea, acid, organic solvents, trypsin, plasmin and heating at 95 degrees C for 5 min. These properties suggested that both growth inhibitors might be distinct from known growth-inhibitory factors.
Division of Enzymology, Institute for Protein Research, Osaka University, Japan.
T
T
Kimura
K
K
Miyazaki
J
J
Yamashita
T
T
Horio
T
T
Kakuno
D000818:Animals; D001798:Blood Proteins / Q000302:isolation & purification* / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects*; D002460:Cell Line; D006131:Growth Inhibitors / Q000097:blood / Q000302:isolation & purification* / Q000494:pharmacology; D007372:Interferons / Q000494:pharmacology; D011817:Rabbits; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D001798:Blood Proteins; D006131:Growth Inhibitors; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; D007372:Interferons