Inducible expression of the gamma-glutamylcysteine synthetase light subunit by t-butylhydroquinone in HepG2 cells is not dependent on an antioxidant-responsive element.

Mutation analysis of putative regulatory elements located in the 5'-flanking region of the gene encoding the regulatory subunit of gamma-glutamylcysteine synthetase (GLCLR) revealed that neither an antioxidant-responsive element (ARE) nor an activator protein-1 (AP-1) site regulates inducible expression by t-butylhydroquinone (tBHQ). The AP-1 site was found to modulate basal expression of GLCLR. A 42 bp region between nucleotides -303 and -344, not containing an ARE, was found to regulate inducible expression of GLCLR by tBHQ.