PBX/Knotted 1 Homeobox Protein 2 (PKNOX2)

PKNOX2 contains 2 N-terminal regions, HR1 and HR2, homologous to regions in PKNOX1 and MEIS proteins, followed by an atypical homeodomain characteristic of TALE family members and a C-terminal lysine-rich nuclear localization signal. The homeodomains of PKNOX1 and PKNOX2 share 94% identity. Northern blot analysis detected a 4.6-kb PKNOX2 transcript. Expression was highest in brain and skeletal muscle, moderate in pancreas, lung, heart, kidney, small intestine, thymus, spleen, and kidney, and very low in colon, liver, and peripheral blood leukocytes.The expression pattern of PKNOX2 differed from that of PKNOX1, suggesting that the proteins have distinct roles. Epitope-tagged PKNOX2 was expressed in the nucleus, but not in nucleoli, of transfected COS-7 cells.