A highly conserved, 5' untranslated, inverted repeat sequence is ineffective in translational control of the alpha...

An inverted repeat sequence, extending from the 5' untranslated region of the first exon through the translation initiation codon, is highly conserved in the alpha 1(I), alpha 2(I) and alpha 1(III) collagen genes of mammals and birds. It has been suggested that this sequence functions in translational control of collagen gene expression. When the upstream axis of the dyad of symmetry was deleted, the efficiency of translation of transcripts from a human alpha 1(I) collagen-bovine growth hormone fusion gene was unchanged in either transiently or stably transfected cells. Furthermore, mRNA levels were not affected when the same deletion was transferred to a collagen-human growth hormone fusion gene in which the collagen sequence retained the first intron. Examination of human alpha 1(I) DNA, extending from the start of transcription to the start of translation, by the DNAse I protection procedure revealed evidence for protein binding to a sequence just upstream of the inverted repeat sequence but not to the inverted repeat itself. Our studies therefore indicate that this highly conserved DNA sequence does not function generally in translational or transcriptional control of type I procollagen synthesis.