Figure 1.

Splicing enhances mRNA polysome association. (A,D) Schematic representation of TCR-β and β-globin constructs. Boxes represent exons, and lines connecting them denote introns. RPA probes are indicated by heavy lines. (B,C,E,F) Sucrose gradient fractionation of cytoplasmic extracts from cells expressing no-intron or intron-containing versions of TCR-β and β-globin. RNA extracted from each fraction (see Materials and Methods) was subject to RPA with probe E or J (A,D) and a probe specific to endogenous cyclophilin mRNA. Protected fragments were separated on a 10% denaturing polyacrylamide gel. Relative absorbance at 254 nm is depicted by thin lines, and the percent total mRNA in each fraction is shown by the dashed lines (scale on right).