A p32 component from rabbit reticulocyte lysate binds to E7 mRNA-conjugated Dynabeads. For SDS-PAGE characterization of the E7 mRNA-binding protein purified by magnetic affinity, rabbit reticulocyte lysate was incubated in binding buffer with HPV16 E7 mRNA-activated magnetic beads. Following washings, the reticulocyte component fraction bound to Dynabeads was eluted and electrophoresed in SDS-12.5% PAGE. The gel was silver stained. Lanes: 1, whole rabbit reticulocyte lysate used for magnetic separation; 2, protein eluted with 1 M NaCl from the activated magnetic beads; 3, unbound proteins. Numbers on the left indicate positions of molecular mass standards (in kilodaltons).