Crystallographic identification and functional characterization of phospholipids as ligands for the orphan nuclear receptor steroidogenic factor-1.
Li, Y., Choi, M., Cavey, G., Daugherty, J., Suino, K., Kovach, A., Bingham, N., Kliewer, S., Xu, H.(2005) Mol Cell 17: 491-502
- PubMed: 15721253 
- DOI: https://doi.org/10.1016/j.molcel.2005.02.002
- Primary Citation of Related Structures:  
1YP0 - PubMed Abstract: 
The orphan nuclear receptor steroidogenic factor 1 (SF-1) regulates the differentiation and function of endocrine glands. Although SF-1 is constitutively active in cell-based assays, it is not known whether this transcriptional activity is modulated by ligands. Here, we describe the 1.5 angstroms crystal structure of the SF-1 ligand binding domain in complex with an LXXLL motif from a coregulator protein. The structure reveals the presence of a phospholipid ligand in a surprisingly large pocket (approximately 1600 angstroms3), with the receptor adopting the canonical active conformation. The bound phospholipid is readily exchanged and modulates SF-1 interactions with coactivators. Mutations designed to reduce the size of the SF-1 pocket or to disrupt hydrogen bonds with the phospholipid abolish SF-1/coactivator interactions and significantly reduce SF-1 transcriptional activity. These findings provide evidence that SF-1 is regulated by endogenous ligands and suggest an unexpected relationship between phospholipids and endocrine development and function.
Organizational Affiliation: 
Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Avenue, Grand Rapids, MI 49503, USA.