PREP1 (named PKNOX1, Pbx/KNOX 1) was identified by Chen et al. (1997) in their effort to characterize genes mapping in the human chromosome 21. At the same time, PREP1 was identified as one of the components of the human transcription factor complex UEF3, urokinase enhancer factor 3. Prep1 was found to be a homeodomain-containing DNA-binding protein belonging to the TALE (Three Aminoacid Loop Extension) superclass, most closely related to TGIF (TGF β–induced factor homeobox) and Meis1 (Meis homeobox 1) and recognizing the TGACAG motif. Furthermore, it has been demonstrated that Prep1 heterodimerizes with Pbx, enhancing its affinity and DNA-binding specificity to include both the TGACAG and the TGATNNAT motifs (hence the acronym, for Pbx regulating protein 1) (Berthelsen et al. 1998).
PREP2 was identified by Imoto et al. (2001) as a TALE homeodomain-encoding gene, located at 11q24 in the human genome.
Gene and Protein Structure
The human PREP1 gene...
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