Ankyrin Repeat Domain Protein 28 (ANKRD28)

ANKRD28 selectively inhibited the phosphorylase activity of PP1C in a dose-dependent manner. Phosphorylation of ser1013 and ser1017, which lie within the putative PP1-binding motif, negatively regulated ANKRD28 binding to PP1C. Immunoprecipitation studies showed that ANKRD28 bound to hnRNP-K .ANKRD28 selectively regulated phosphorylation of hnRNP-K at ser284, an effect that was enhanced in vivo by an S1013A/S1017A double mutant, suggesting that ANKRD28 targets PP1 in a regulated manner to dephosphorylate hnRNP-K selectively at ser284. Microarray analysis found that expression of ANKRD28 resulted in altered expression of 47 genes, including marked induction of MEK5 (MAP2K5).