NUCLEAR RECEPTOR-BINDING FACTOR-I (NRBF-1), A PROTEIN INTERACTING WITH A WIDE SPECTRUM OF NUCLEAR HORMONE RECEPTORS

To identify the proteins which may modulate the functions of peroxisom e proliferator-activated receptor (PPAR), a rat liver cDNA Library was screened by a yeast two-hybrid system, using the mouse PPAR alpha as a bait. A protein named nuclear receptor binding factor-1 (NRBF-1) was identified, which interacts not only with PPAR alpha, but also with v arious nuclear hormone receptors in the presence of the respective lig ands. Both the hinge and ligand-binding domains of PPARa are required for the interaction. NRBF-1 seems to be translocated to the nucleus by a piggyback mechanism, together with PPAR alpha. NRBF-1 has a signifi cant homology to the yeast protein MRF1, a putative transcription fact or regulating the expression of mitochondrial respiratory proteins. NR BF-1 might be another type of nuclear receptor co-operator. (C) 1998 E lsevier Science B.V. All rights reserved.