An S1 nuclease-sensitive homopurine/homopyrimidine domain in the PDGF A-chain promoter contains a novel binding site for the growth factor-inducible protein EGR-1.

Transcription of the platelet-derived growth factor (PDGF) A-chain gene is activated in cells exposed to growth factors. We now have identified a homopurine/homopyrimidine domain in the promoter region of the PDGF A-chain gene that exhibits S1 nuclease sensitivity in vitro and that contains a novel binding site (5'-TCCTCCTCCTCCTC-3') for the growth factor inducible transcription factor EGR-1 as demonstrated in gel mobility shift assays. Sequences similar to this novel EGR-1 binding site were observed also in five growth-related genes and shown to bind to EGR-1 in competition assays, suggesting that EGR-1 may influence the transcriptional regulation of these growth-related genes.