Fig. 5.

Nuclear hnRNP A1 binds the LRE directly. (A) Electrophoretic mobility shift analysis of binding of GST (500 nM) and GST-hnRNP A1 (45, 90, 180 nM) to [α-³²P] rUTP-labelled LRE or truncated LRE RNA probes. The probes used are shown in Fig. 1 and indicated below the autoradiograph. Arrows indicate free probe. A bracket indicates RNA/protein complexes. (B) Competition electrophoretic mobility shift experiment using a non-specific competitor, unlabelled in vitro-transcribed pBluescript polylinker RNA (70 nts) (pBS) (lanes 1–5) or a specific competitor, unlabelled in vitro transcribed LRE RNA (79 nts) (lanes 6–10). P; [α-³²P] rUTP-labelled LRE probe alone, N; probe plus nuclear extract. Both competitors were added to reactions at 1, 2, 4, 8 and 16-fold molar excess. Arrows indicate free probe. A bracket indicates protein/RNA complexes.