There are six ankyrin repeats in yeast transcriptional factor PHO81. The PHO81 ankyrin repeats fused with glutathione S-transferase (GST-ANK) was overexpressed in E. coli  and it existed in inclusion body form. Using reduced and oxidized glutathione systems  the fused protein fragment was denatured and renatured  and the soluble protein was obtained. Then it was purified by affinity purification through glutathione sepharose column and its activity was analyzed. The PHO85-PHO80 and PHO85-PAP1 kinase complexes were prepared via coimmunoprecipitation respectively. With purified recombinant PHO4 protein as substrate of the kinase complexes  when the purified GST-ANK was added  the kinase activity of PHO85-PHO80 or PHO85-PAP1 kinase complex was inhibited. These studies indicate that the ankyrin repeats interact with PHO85-PHO80 or PHO85-PAP1 complex  inhibit their kinase activities  and are crucial in interaction between PHO81 and other proteins.