CDNA CLONING AND CHROMOSOME MAPPING OF THE HUMAN FE65 GENE - INTERACTION OF THE CONSERVED CYTOPLASMIC DOMAINS OF THE HUMAN BETA-AMYLOID PRECURSOR PROTEIN AND ITS HOMOLOGS WITH THE MOUSE FE65 PROTEIN

Using the yeast two hybrid system, a mouse embryo cDNA library was scr eened for proteins that interact with the C-terminus of the human beta -amyloid precursor protein (PPP), A fusion protein was identified that interacts specifically with the cytoplasmic domain of PPP and does no t interact with the beta-amyloid region, The protein encoded by this p artial mouse cDNA is identical to the C-terminus of the rat Fe65 prote in, This mouse protein also interacts with the homologous C-terminal d omains of the mouse amyloid precursor-like proteins, APLP1 and APLP2, These conserved cytoplasmic regions contain a common amino acid motif, Asn-Pro-Thr-Tyr, which has previously been shown to influence both th e secretion and internalization of PPP. Fe65 has been implicated in re gulatory and cell signaling mechanisms because it contains two differe nt motifs involved in protein binding, a WW domain (a variant of Src h omology 3 domains) and a phosphotyrosine interaction domain (PID). Int erestingly, the PID domain binds to the same motif present in the cons erved cytoplasmic domains of the PPP and PPP-like proteins, RNA analys es reveal that Fe65 is predominantly expressed in brain and in the reg ions most affected by Alzheimer's disease (AD)-associated neuropatholo gy, The human Fe65 mRNA was cloned from a fetal brain cDNA library. Th e message encodes a protein of 735 amino acids that is 95% identical t o the rat Fe65 protein. The human Fe65 gene was mapped on human metaph ase chromosomes to band 11p15 using fluorescence in situ hybridization .