title: G2 phase-specific proteins of HeLa cells.
abstract: The objective of this study was to determine if HeLa cells irreversibly arrested in G2 phase of the cell cycle by a brief exposure to a nitrosourea compound were deficient in certain proteins when compared with G2-synchronized cells. Total cellular proteins of G2-synchronized, G2-arrested, and S phase-synchronized cells were compared by two-dimensional polyacrylamide gel electrophoresis. The S phase cells differed from the G2-synchronized and G2-arrested cells by the absence of about 35 and 25 protein spots, respectively, of a total of nearly 150. At least nine protein spots in the molecular weight range of 4--5 X 10(4) that were present in the G2-synchronized cells were absent in both the G2-arrested and the S phase cells. Thus, these studies suggest that the missing proteins are probably necessary for the transition of cells from G2 phase to mitosis. Supplying the missing proteins to the G2-arrested cells by fusion with G2-synchronized cells facilitated the entry of the former into mitosis.
mesh_terms: D002453:Cell Cycle / Q000187:drug effects; D002459:Cell Fusion; D004261:DNA Replication; D006367:HeLa Cells; D008938:Mitosis / Q000187:drug effects; D009607:Nitrosourea Compounds / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism*; D012313:RNA / Q000096:biosynthesis
chemical_list: D009607:Nitrosourea Compounds; D011506:Proteins; D012313:RNA