CONSERVATION OF BINDING-SITES FOR REGULATORY FACTORS IN THE COORDINATELY EXPRESSED ALPHA-1(I) AND ALPHA-2(I) COLLAGEN PROMOTERS

To examine possible mechanisms for the coordinate control of the α1(I) and α2(I) collagen genes, we have searched for DNA binding factors that are common to both genes. We have recently identified in the proximal part of the α1(I) promoter a functional binding site for CBF, a heteromeric transcriptional activator which binds to certain CCAAT sequences, and also functional binding sites for two different transcriptional repressors, designated IF1 and IF2. CBF was previously also shown to bind and activate the α2(I) collagen promoter. We now present evidence that a factor with similar binding characteristics as IF1 binds to the α2(I) promoter at approximately the same distances from the start site of transcription as in the α1(I) collagen promoter. A three bp substitution mutation in the IF1 binding site which abolishes IF1 binding increases the activity of the α2(I) promoter 4-fold as with the α1(I) promoter. We propose that the coordinate regulation of these two genes is at least in part mediated by these common elements. © 1991.