The objective of this study is to dissect a mechanism of gene regulation by Steroidogenic Factor 1 (SF-1). The underlying hypothesis is that SF-1 functions as a mediator of discrete activation domains which are modulated by specific cofactors or coactivators. In order to test this hypothesis, the investigators will conduct a detailed structural functional analysis of SF-1. They will attempt to identify putative activation domains of SF-1, examine the activation capacity in the context of heterologous proteins, and determine their independent function in steroidogenic as well as nonsteroidogenic cell lines. Further studies will examine whether transcriptional activation by SF-1 requires interaction of its activation domain with cofactors. These cofactors will be identified using a yeast two-hybrid system.