Fe65 is an adaptor protein that interacts with the Alzheimer beta-amyloid 
precursor protein and is expressed mainly in the neurons of several regions of 
the nervous system. The FE65 gene has a TATA-less promoter that drives an 
efficient transcription in cells showing a neuronal phenotype, whereas its 
efficiency is poor in non-neuronal cells. A short sequence encompassing the 
transcription start site contains sufficient information to drive the 
transcription in neuronal cells but not in non-neural cells. Electrophoretic 
mobility-shift assays performed with rat brain nuclear extracts showed that 
three major DNA-protein complexes, named BI, BII and BIII, are formed by the 
FE65 minimal promoter. The proteins present in complexes BI and BII were 
purified from bovine brain; internal microsequencing of the purified proteins 
demonstrated that they corresponded to the previously isolated 
single-stranded-DNA-binding protein Pur alpha, abundantly expressed in the 
brain. In Chinese hamster ovary (CHO) cells, where the efficiency of FE65 
promoter is very low, transient expression of Pur alpha increased the 
transcription efficiency of the FE65 minimal promoter. By using oligonucleotide 
competition and a specific antibody we demonstrated that the transcription 
factor YY1 is responsible for the formation of complex BIII. Also in this case, 
the transient expression of the YY1 cDNA in CHO cells resulted in an increased 
transcription from the FE65 minimal promoter. The absence of any co-operative 
effect when CHO cells were co-transfected with both YY1 and Pur alpha cDNA 
species suggests that two different transcription regulatory mechanisms could 
have a role in the regulation of the FE65 gene.