HIPK2 associates with RanBPM.

Using the yeast two-hybrid system, we have identified the Ran-binding protein (RanBPM) as an interaction partner of homeodomain-interacting protein kinase 2 (HIPK2). RanBPM has been described as a centrosomal protein through which Ran regulates the centrosomal function. HIPK2 is mainly a nuclear protein, which among other functions represses transcription mediated by homeodomain containing transcription factors. Here, we show that overexpressed wildtype HIPK2 and a kinase defective mutant of HIPK2 directly interact with RanBPM in the nucleus of mammalian cells. Overexpressed wildtype RanBPM and a kinase defective mutant of HIPK2 co-localise with HIPK2 in defined nuclear structures. A carboxy- and an amino-terminal deletion of HIPK2 do not seem to be able to bind to RanBPM.