Highly conserved glucose-regulated protein in hamster and chicken cells: preliminary characterization of its cDNA...

A temperature-sensitive mutant K12 derived from a Chinese hamster fibroblast has been shown to overproduce three specific proteins of Mr 94,000, 78,000, and 58,000 when incubated at the nonpermissive temperature (40.5 degrees C). We previously identified these proteins as glucose-regulated proteins similar to those observed in chicken embryo fibroblasts when the cells are starved of glucose. In this report, we show that the Mr 78,000 proteins isolated from the hamster K12 cell line and from chicken embryo fibroblasts have identical electrophoretic mobilities in two-dimensional isoelectric focusing gels and nearly identical peptide maps. However, these proteins are different from heat-shock proteins previously described for animal cells. We have constructed a library of cDNA clones by using the RNA extracted from the hamster K12 cells incubated at 40.5 degrees C. Clones that hybridize preferentially with cDNA made from RNA at 40.5 degrees C were selected. By using the hybrid-selection technique, followed by in vitro translation, a cDNA clone containing a 2550-nucleotide insert coding for the hamster Mr 78,000 protein has been identified.