Identification of Candidate Proteins Binding to Prion Protein

Abstract

Prion diseases are disorders of protein conformation that produce neurodegeneration in humans and animals. Studies of transgenic (Tg) mice indicate that a factor designated protein X is involved in the conversion of the normal cellular prion protein (PrP C) into the scrapie isoform (PrP Sc); protein X appears to interact with PrP Cbut not with PrP Sc. To search for PrP Cbinding proteins, we fused PrP with alkaline phosphatase (AP) to produce a soluble, secreted probe. PrP–AP was used to screen a λgt11 mouse brain cDNA library, and six clones were isolated. Four cDNAs are novel while two clones are fragments of Nrf2 (NF-E2 related factor 2) transcription factor and Aplp1 (amyloid precursor-like protein 1). The observation that PrP binds to a member of the APP (amyloid precursor protein) gene family is intriguing, in light of possible relevance to Alzheimer's disease. Four of the isolated clones are expressed preferentially in the mouse brain and encode a similar motif.