Integrin Beta 3 Binding Protein (ITGb3BP)

NRIF3 protein utilized both its C- and N-terminal receptor-interacting domain to cooperatively interact with THRA or RXR, with the spacing between these domains influencing the affinity of the interactions. Mutagenesis analysis also revealed a central NRIF3-NRIF3 interaction domain. Reporter gene assays showed that the isolated C-terminal domain of NRIF3 activated transcription, while the full-length protein repressed transcription. Both of the shorter NRIF3 isoforms have the repressor domain and coiled-coil dimerization domain, but they lack the C-terminal transcriptional activation domain found in the full-length isoform. Reporter gene activity confirmed their function as a transcriptional repressors. Immunofluorescence microscopy localized all 3 NRIF3 isoforms to the nucleus.