Phorbol ester, calcium ionophore, or serum added to quiescent rat embryo fibroblast cells all result in the elevated phosphorylation of two 28,000-dalton mammalian stress proteins.
Rat embryo fibroblast cells grown under stress (e.g. heat shock, arsenite, or amino acid analogue treatment) show elevated levels of a number of proteins with apparent molecular masses between 28,000-110,000 daltons (i.e. stress proteins). It is shown that the smaller 28,000-dalton stress proteins, which do not contain methionine, are comprised of at least four isoforms, all of which appear related as determined by one-dimensional peptide mapping. [32P]H3PO4 labeling of normal and stressed cells demonstrates that three of the four 28-kDa isoforms are phosphoproteins. In the course of other studies phosphorylation of two 28,000-dalton proteins was observed in quiescent rat embryo fibroblasts following the addition of either the phorbol diester, phorbol-12-myristate-13 acetate, a calcium ionophore, A23187, or simply fresh serum. It is shown here that these two 28,000-dalton proteins are in fact two of the 28 kDa mammalian stress proteins.
D000818:Animals; D001769:Blood; D000001:Calcimycin / Q000494:pharmacology*; D010450:Endopeptidases / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism*; D007930:Leucine / Q000378:metabolism; D008970:Molecular Weight; D010704:Phorbols / Q000494:pharmacology*; D010750:Phosphoproteins / Q000032:analysis; D010766:Phosphorylation; D011247:Pregnancy; D051381:Rats; D012697:Serine Endopeptidases; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D006360:Heat-Shock Proteins; D010704:Phorbols; D010750:Phosphoproteins; D000001:Calcimycin; D010450:Endopeptidases; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D007930:Leucine; D013755:Tetradecanoylphorbol Acetate