RNA PROTEIN INTERACTIONS IN THE 5' UNTRANSLATED REGION OF PREPROINSULIN MESSENGER-RNA

A comparison between species of the 5' untranslated region of preproinsulin mRNA revealed conserved sequences associated with a potential stem-loop structure. The present study was undertaken to determine whether specific protein interactions exist with mRNA sequences involved in the formation or stabilization of this structure in the 5' untranslated region. P-32-Labelled RNA probes corresponding to sequences from this region were synthesized by an in-vitro transcription reaction and used in electrophoretic mobility shift and u.v.-crosslinking studies with cytoplasmic protein extracts from a number of cell lines. Specific protein-RNA interactions were mapped to a sequence located between nucleotides -21 and -50 upstream of the AUG start codon. A number of proteins of molecular mass 25kDa, 40kDa, 46kDa, 58kDa, 69kDa, 97kDa, 110kDa and l60kDa were specifically crosslinked to this sequence. The observed specific protein-RNA interactions in the 5' untranslated region may affect the activity of preproinsulin mRNA.