Insulin-responsive tyrosine aminotransferase transcription requires multiple promoter regions

This study used transient transfection analysis to determine the DNA regions which mediate basal and insulin-sensitive transcription from the gene encoding tyrosine aminotransferase (TAT; EC 2.6.1.5). Basal expression requires at least parts of two regions: a region at -3600 and a region from -208 to + 62. Insulin sensitivity requires at least one region of the promoter not required for basal expression. Thus, insulin cannot act solely by direct modification of any of the components required for basal transcription. Previous results from this laboratory suggest that the insulin effects on basal and glucocorticoid-induced TAT transcription require different regions of the proximal promoter.