Homeodomain Interacting Protein Kinase 3 (HIPK3)

Protein kinases are involved not only in cellular regulation and signaling but also in multidrug resistance (MDR). HIPK3 contains sequences identical to the catalytic core of many serine-protein kinases and is 54% similar to the yeast protein kinase YAK1, whose normal role is to restrict growth. The authors therefore designated the protein PKY, for homolog of protein kinase YAK1. PKY was expressed at higher levels in MDR cells than in their nonresistant parental lines; in addition, a 7-kb PKY transcript was expressed at high levels in heart and skeletal muscle and at lower levels in placenta, pancreas, and brain.The deduced amino acid sequence is identical for the first 407 amino acids, followed by introduction of 4 novel amino acids and a stop codon, possibly resulting in nonsense-mediated decay.