Binding of sequence-specific proteins to the 3'-untranslated region of vasoactive intestinal peptide mRNA.
Multimeric AUUUA elements in an AU-rich 3'-untranslated region (3'-UTR) have been shown to confer message instability to numerous ephemeral transcripts through the formation of RNA-protein complexes. We show here that the 3'-UTR of VIP mRNA, which contains 3 AUUUA motifs in an AU-rich context, forms specific complexes with cytoplasmic proteins in a concentration-dependent, tissue-specific manner. We also demonstrate that an AU-rich segment of c-fos mRNA can successfully compete with VIP mRNA for binding with cytoplasmic proteins. These studies provide the first evidence for a mechanism by which VIP is post-transcriptionally regulated through specific sequences in its 3'-UTR.