Multiple GF-1 binding sites flank the erythroid specific transcription unit of the human carbonic anhydrase I gene.

Six potential GF-1 sites which bind an erythroid factor are present in the 5' and 3' regions flanking the erythroid-specific transcription unit of the human carbonic anhydrase I (HCAI) gene. When two of these sites are placed upstream of a minimal eukaryotic promoter they confer up-regulated expression in erythroid over non-erythroid cells. The presence of the erythroid factor in TPA-treated HEL cells in which the level of HCAI transcript has greatly decreased and in non-HCAI-expressing K562 cells suggests that in these cases the presence of the factor is not sufficient for HCAI expression.