Figure 2.

(A) Effect of vitamin K or warfarin on the synthesis of total secretory proteins in HEK293 cells. Confluent cells were incubated with vitamin K (K) or warfarin (W) in the presence of [³⁵S]methionine. Media were withdrawn at the times indicated and centrifuged to remove cell debris, and protein was precipitated with 10% trichloroacetic acid. Precipitated radioactivity was determined by liquid scintillation spectrometry. (B) Effect of vitamin K or warfarin on the rate of biosynthesis of rFII in HEK293 cells. HEK293 cells were transfected with pcDNA3-RFII. After 24 h, the cells were incubated for 24 h followed by a 5-min pulse-labeling with [³⁵S]methionine. Prothrombin in cellular lysates from three flasks was immunoprecipitated and detected by SDS/PAGE and fluorography. The position of an 84-kDa molecular mass standard is indicated. In two experiments, the amount of [³⁵S]prothrombin in the warfarin-treated cells was 110% and 106% that of the vitamin K-treated cells.