Figure 3.

RNA also elicits hyperphosphorylation of endogenous C1 hnRNP protein in nuclear extract. HeLa nuclear extract (not pretreated with micrococcal nuclease) was incubated for 30 min (at 30°C) in the presence or absence of added nuclear extract RNA (final concentration of added RNA, 75 μg/ml) and then for an additional 60 min (at 30°C) with [γ-³²P]GTP. The reactions were then processed as described followed by incubation with protein A-Sepharose coupled 4F4 monoclonal antibody for 2 hr at 4°C. After washing the resin, the bound C1 hnRNP protein was eluted (4, 5, 9, 10) and analyzed by electrophoresis and autoradiography. Lanes: 1, no added RNA; 2, added nuclear extract RNA.