QM is a novel zinc-binding transcription regulatory protein: Its binding to c-Jun is regulated by zinc ions and phosphorylation by protein kinase C

A novel method was developed for cloning of zinc-binding proteins, We used Zn-65(2+) as a probe to screen a human lung cDNA library, and isolated QM using this approach. QM appears to be a negative regulator of c-Jun that acts by binding to the leucine zipper region of c-Jun, We demonstrated that QM bound zinc ions and that such binding was necessary for the interaction of QM with c-Jun. We also showed that protein kinase C introduced about 1 mol of phosphate into 1 mol of QM. The binding of QM to c-Jun was decreased by 60% when QM had been phosphorylated. These results suggest that QM is a novel zinc-binding transcription regulatory protein and that interaction between QM and c-Jun is regulated by zinc ions and phosphorylation. (C) 1997 Academic Press