PQBP-1 (Np/PQ): A polyglutamine tract-binding and nuclear inclusion-forming protein

Polyglutamine(Q) tract binding protein-1 (PQBP-1) was isolated on the basis of its interaction with polyglutamine tracts and localizes predominantly t o the nucleus where it suppresses transcriptional activation by a neuron-sp ecific transcription factor, Brn-2. Its C-terminal domain is highly conserv ed and binds to a component of the spliceosome. PQBP-1 possesses unique rep etitive sequences that may fold as polar zippers. Interestingly, PQBP-1 als o forms nuclear inclusion bodies, which are similar to those nucleated by t he protein products of polyglutamine disease genes. Furthermore, because PQ BP-1 is highly conserved in simple animal metazoans and plants (Caenorhabdi tis elegans and Arabidopsis), it may perform a basic function in cells. By the same token, disruption of the basic function could be critical to the d isease process. Collectively, PQBP-1 might be a candidate molecule involved in the pathology of polyglutamine diseases. In this review, we discuss the structure and function of the PQBP-1 protein, the relevance of its aggrega tion and possible roles in normal and disease processes. (C) 2001 Elsevier Science Inc.