Paired Related Homeobox Protein 1 (PRRX1)

PRRX1 is a member of the paired family of homeobox proteins localized to the nucleus. The protein functions as a transcription co-activator, enhancing the DNA-binding activity of serum response factor, a protein required for the induction of genes by growth and differentiation factors. The protein regulates muscle creatine kinase, indicating a role in the establishment of diverse mesodermal muscle types. In human embryonic tissues, the exon 4-containing PRRX1 splice variant was more highly expressed in skeletal muscle and heart than the shorter transcript. All other embryonic tissues expressed both transcripts equally or expressed predominantly the shorter form. Conversely, the exon 4-containing transcript was expressed at higher levels than the shorter transcript in all adult tissues examined.