The metastasis suppressor candidate nucleotide diphosphate kinase NM23 specifically interacts with members of the ROR/RZR nuclear orphan receptor subfamily.

We have cloned proteins that interact with the nuclear orphan receptor RZR beta using the yeast two-hybrid system. We identified, amongst a number of other genes, the nucleoside diphosphate kinase (NDPK)-2 also known as Nm23-2, c-myc regulatory factor PuF and differentiation inhibitory factor, RZR beta specifically interacts with Nm23-2 but not with the closely related tumor metastasis suppressor candidate gene product Nm23-1. In contrast ROR alpha interacts with both Nm23 proteins. These findings were corroborated by in vitro interaction assays based on GST-pulldown experiments. With-n-myc we propose a candidate gene regulated by ROR alpha/RZR beta and Nm23, based on the finding that the respective DNA binding sites in the first intron are conserved in several mammalian species.