HuR binds in a specific manner to the CD83 PRE RNA region.

<p><b>A.</b> Increasing amounts of bacterial expressed GST-HuR protein was incubated either with the radiolabelled CD83 mRNA wildtype (wt) coding sequence (CD83wt; lane 1–7) or the respective probe lacking the HuR target sequence PRE (CD83ΔPRE; lane 8–14). Complex formation was visualized by gel retardation assay and autoradiography. Lane 1: CD83wt RNA alone; lane 2: GST negative control; lane 3–7 increasing amounts of GST-HuR (0.095–0.475 µM); lane 8: CD83ΔPRE alone; lane 9: GST negative control; lane 10–14: increasing amounts of GST-HuR (0.095–0.475 µM). <b>B.</b> Analysis of PRE binding specificity by competition experiments. GST-HuR protein (lane 2–4 and lane 11–13: 0.119 µM, 0.238 µM, 0.475 µM, respectively; lane 5–9 and 14–18: 0.475 µM, respectively) or GST (1 µM) for negative control (lane 1 and 10) was incubated together with radiolabelled CD83wt PRE mRNA and analyzed as before. Increasing amounts (1–5 fold excess over CD83wt PRE mRNA) of either unlabelled HIV-1 RRE RNA (lane 5–9) or unlabelled TNFα ARE RNA (lane 14–18) were added to individual binding reactions.