CLONING AND CHARACTERIZATION OF HUR, A UBIQUITOUSLY EXPRESSED ELAV-LIKE PROTEIN

The neuronal-specific Elav-like proteins (HuD, Hel-N, and HuC) contain three RNP-type concensus motifs and bind to AU-rich elements. We have identified and cloned a fourth member of this family (HuR) that is ex pressed in a wide variety of cell types. The purified recombinant prot ein binds avidly to the AU-rich element in c-fos and interleukin-3 mRN As, In the case of the c-fos AU-rich element, HuR binds to a core elem ent of 27 nucleotides that contain AUUUA, AUUUUA, and AUUUUUA motifs. Mutational analysis has shown that all three AU motifs are required fo r maximal binding.