PBX/Knotted 1 Homeobox Protein 1 (PKNOX1)

As part of developing a transcript map of human chromosome 21, Chen et al. (1997) used exon trapping to identify portions of genes from chromosome 21-specific cosmids. Using the exon and EST as probes, they screened human fetal brain and kidney cDNA libraries and cloned the corresponding gene, which encodes a homeodomain-containing polypeptide of 436 amino acids. Chen et al. (1997) used the EST as a probe for Northern analysis and detected transcripts of 2.5 and 5 kb in every human tissue examined, including heart, brain and brain subregions, placenta, lung, liver, muscle, and several fetal tissues. The gene, designated PBX/knotted-1 homeobox-1 (PKNOX1), has a homeodomain closely related to those of the mammalian PBX family and the plant knotted-1 family.