The activation function of steroidogenic factor-1 is impaired in ACTH-resistant Y1 mutants.

This study explores the basis for the altered function of steroidogenic factor-1 (SF1) in a family of ACTH-resistant Y1 adrenal cell mutants. As determined in electrophoretic mobility shift assays, the DNA binding activity of SF1 was not impaired in the mutant clones. Instead, the ability of SF1 to interact with the coactivator, GRIP1 was affected as determined in a modified mammalian 2-hybrid assay. These findings indicate that the mutants harbor a defect affecting the activation function of SF1.