Inositol 1,3,4-trisphosphate 5/6-kinase associates with the COP9 signalosome by binding to CSN1.
The COP9 signalosome (CSN) is a complex of eight proteins first identified as a repressor of plant photomorphogenesis. A protein kinase activity associated with the COP9 signalosome has been reported but not identified; we present evidence for inositol 1,3,4-trisphosphate 5/6-kinase (5/6-kinase) as a protein kinase associated with the COP9 signalosome. We have shown that 5/6-kinase exists in a complex with the eight-component COP9 signalosome both when purified from bovine brain and when transfected into HEK 293 cells. 5/6-kinase phosphorylates the same substrates as those of the COP9 signalosome, including IkappaBalpha, p53, and c-Jun but fails to phosphorylate several other substrates, including c-Jun 1-79, which are not substrates for the COP9-associated kinase. Both the COP9 signalosome- associated kinase and 5/6-kinase are inhibited by curcumin. The association of 5/6-kinase with the COP9 signalosome is through an interaction with CSN1, which immunoprecipitates with 5/6-kinase. In addition, the inositol kinase activity of 5/6-kinase is inhibited when in a complex with CSN1. We propose that 5/6-kinase is the previously described COP9 signalosome-associated kinase.
D000595:Amino Acid Sequence; D000075686:COP9 Signalosome Complex; D002850:Chromatography, Gel; D003474:Curcumin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D046912:Multiprotein Complexes; D010447:Peptide Hydrolases; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*
D004791:Enzyme Inhibitors; D046912:Multiprotein Complexes; D011506:Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); C056875:myo-inositol-trisphosphate 6-kinase; D010447:Peptide Hydrolases; D000075686:COP9 Signalosome Complex; D003474:Curcumin