FIG. 4.

Human Y RNA is required for the reconstitution of chromosomal DNA replication. (A) Schematic drawing of the expression constructs for full-length human RNAs. (B) In vitro synthesis of full-length human wild-type RNA. Individual recombinant RNAs were synthesized in vitro from the constructs shown in panel A and visualized by SYBR green staining after denaturing gel electrophoresis. Multimeric 100-nucleotide (nt) RNA fragments were used for a molecular weight marker (lane M). (C) Functional reconstitution of chromosomal DNA replication with hY RNAs. n, number of experiments. Nuclei from late-G₁-phase cells were incubated with fractions QA and ArFT, supplemented with 100 ng of the individual RNAs synthesized in vitro as indicated. Proportions of replicating nuclei were determined as described in the legend to Fig. 1.