FIG. 6.
Determination of SLBPs bound to histone mRNA during oogenesis. Extracts from stage II (lanes 1, 5, and 9), stage IV (lanes 2, 6, and 10), and stage VI (lanes 3, 7, 11, 13, 15, and 17) oocytes, oocytes matured in vitro with progesterone (lanes 4, 8, and 12), or eggs (lanes 14, 16, and 18) were incubated with antibodies to either frog SLBP1 (lanes 1 to 4, 13, and 14), frog SLBP2 (lanes 5 to 8, 15, and 16), or mouse SLBP (lanes 9 to 12, 17, and 18). The RNAs bound to the antibodies were isolated and assayed by S1 nuclease mapping for frog histone H2a mRNA (top). RNA was also prepared from the supernatant after incubation with antibody and protein A-agarose and assayed for frog histone H2a mRNA by S1 nuclease mapping (bottom). The protected fragments were resolved by gel electrophoresis and detected by autoradiography. The results are representative of three independent experiments. A diagram of the S1 nuclease assay is shown. The mRNA from this H2a gene protects a 224-nt fragment (H2a), and the mRNAs from other H2a genes protect a 180-nt fragment (H2ax) which maps to the stop codon.