Four highly stable eukaryotic mRNAs assemble 3′ untranslated region RNA–protein complexes sharing cis and trans components

Assembly of a sequence-specific RNA–protein complex on the 3′ untranslated region (3′UTR) of human α-globin mRNA (α-complex) correlates with mRNA stabilization. Here we map a limited segment of the α-globin 3′UTR that is both necessary and sufficient for α-complex formation. The sequence of this binding region identifies three additional, highly stable mRNAs that share closely related, pyrimidine-rich cis-motifs in their respective 3′UTRs. Each mRNA assembles a sequence-specific ribonucleoprotein complex at this conserved region. These complexes are structurally related, and each contains a 39-kDa cytoplasmic poly(C) binding protein previously demonstrated to be essential to formation of the α-complex. These observations indicate the existence of a general determinant for stabilization of eukaryotic mRNAs.