The inhibitory effect of the 5 ' untranslated region of muscle acylphosphatase mRNA on protein expression is relieved during cell differentiation

Previous experiments suggested that the upstream AUG triplet present in the 5' untranslated region (UTR) of muscle acylphosphatase mRNA is involved in the regulation of protein expression. In this paper, we study the involvem ent of the 5'UTR secondary structure and upstream peptide on mRNA stability and protein translation. Our data, obtained using deletion and frame-shift mutants, demonstrate that the 5'UTR controls protein expression regulating translation together with mRNA stability. Furthermore, we demonstrate that the inhibitory effect of the 5'UTR of muscle acylphosphatase is relieved d uring the differentiation process in agreement with previous data reporting an increase of acylphosphatase content during cell differentiation. Finall y, UV cross-linking experiments show that specific mRNA-binding proteins ar e associated with the 5'UTR of the muscle acylphosphatase mRNA. (C) 2000 Fe deration of European Biochemical Societies.