Cell cycle-dependent expression of surface antigens in murine T-lymphoma cells: I. Quantitative analysis by SDS-PAGE of antigens from cells in different phases precipitated by antisera against membranes from synchronized cells

Abstract

Studies were undertaken to identify cell surface markers specific for different phases of the cell cycle. Antisera were prepared in rabbits against membrane protein preparations from synchronized BW 5147 cells, an AKR mouse T-lymphoma cell line, in the G1, S, G2 or M phases of the cell cycle. These antisera were used to precipitate radioiodinated surface proteins from synchronized cells in the different phases. The immunoprecipitates were quantitatively analyzed by sodiumdodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Cells in S phase had significantly higher concentrations of proteins weighing 70 × 10 3 and 165 × 10 3 D than cells in G1 or G2 phase. The other major labeled surface components did not vary. These results were confirmed by quantitative absorption of the antisera with synchronized cells. Comparative analysis of the antisera showed that the 165 × 10 3 D peak contained at least two antigens, one recognized by both a-G1 and a-S and the other by a-G1 only. Though cells in S phase had large quantities of the 70 × 10 3 D protein, intact and SDS-solubilized membrane preparations from S phase could not elicit in rabbits any antibody against that protein. These antisera did, however, have good antibody titers to the other major protein peaks and the antisera developed against cells in G1, G2 or M had good anti-70 × 10 3 activity. The results suggest a qualitative molecular change in the 70 × 10 3 protein during S phase.