Influence of monovalent cations on the ratio of RNA transcripts with DNA sequences differing in degree of repetition in leukemia P-388 cells

It was shown on leukemia P-388 cells that a change in the intracellular Na/sup +//K/sup +/ ratio leads to a change in the qualitative composition of the newly synthesized mRNAs, which was recorded according to the change in the kinetics of hybridization of heterogeneous nuclear RNA (hnRNA) with DNA. A decrease in the intracellular Na/sup +//K/sup +/ ratio from 3.8:1 to 1:1 leads to inhibition in the cells of the synthesis of mRNAs that hybridize with DNA at 10/sup 3/ > D/sub o/t > 10/sup 4/ but has little effect on the transcription of the mRNA sequences that hydrolyze with DNA in the range of D/sub o/t from 10/sup 3 x 4/ to 10/sup 3 x 8/. An analogous picture is detected in the hybridization of hnRNA with homogeneous fractions of unique and medium-repetitive DNA sequences. The rate constants of hybridization of hnRNA synthesized by the cells at various ratios of cations and the limiting values of the degree of hybridization (H/sub infinity/) were calculated. It was shown that the rate constants of the hybridization of RNA with DNA decrease by more than two orders of magnitude as they go from the fraction of medium repetitive DNA to the single-copymore » DNA, but in both cases the values are the same for the RNAs synthesized by the cells in the case of various cationic balances.« less