Identification of the glucose/glycosylation-regulated proteins as those which accumulate in the temperature-sensitive cell line K12.

The analysis of proteins synthesized by the temperature-sensitive cell line K12 at the restrictive temperature or after glucose starvation revealed that two main polypeptides were enhanced under both conditions. Besides having the same apparent molecular weights, these new proteins showed identical patterns of partial proteolysis products, irrespective of being isolated from cells incubated at the nonpermissive temperature or from glucose-starved cultures. These results identified the proteins overproduced by K12 cells at 39.5 degrees C as those described in order cell systems, called "glucose/glycosylation regulated proteins" (GR proteins). In addition, it is shown that K12 cells are defective in some step of the glycosylation pathway; this defect may be responsible for the overproduction of GR proteins in K12.