By use of the exonuclease protection assay a protein/DNA interaction site was identified within the rPPT-A promoter, close to the transcriptional start site. In order to map this and any other sites more accurately, DNase1 footprinting analysis was carried out and identified elements were then further characterised by electrophoretic mobility shift assays. Several potential regulatory elements which contain the potential binding sites for a number of distinct transcription factors were identified. These include four AP-1-like sites, one of which also resembles a cyclic AMP response element (CRE), a CCAAT element binding protein (C/EBP) motif, a purine-rich element and six E-box motifs. There are also two regions rich in dT nucleotides, resembling octamer binding protein motifs, and two regions rich in dG nucleotides. Other elements include one located between the TATA box and transcriptional site, another which appears to bind both single-stranded and double-stranded DNA-binding proteins in a tissue specific manner and two elements which have yet to be further characterised. Some of the elements located 3' of the major transcriptional start site differ in their binding characteristics depending on whether extracts of neuronal or non-neuronal tissue were used. The rPPT-A promoter is therefore bound by a variety of proteins, some of which may bind in a tissue-specific manner, thus potentially allowing for stimulus-dependent and tissue-specific gene regulation. It is hoped that the sites identified by this study will act as a foundation for studies of the regulation of the rPPT-A promoter in drg neurons.